Ethically responsible defined as "no stealing" and "no killing" for money leaves a lot of leeway.
For purposes of this answer, I am defining a few additional variables. Please correct me if I am wrong.
- teleportation can be accomplished in any valid combination of mass, distance, and energy required.
- the person must accompany the object being teleported and cannot tele-send or tele-receive to or from a target or person.
- no additional abilities (such as clairvoyance, telepathy, telekinesis, astral projection, or psychometry) are involved or can be used.
- physical touch and/or possession are both valid in order to teleport an object.
- teleportation is a perfect exchange of mass at both destination and departure points, and must be a gaseous substance at the far end. (ie: the target area is perfectly swapped with the initially affected area, and they can't teleport into something solid or liquid. Plus, no thunderclap or other sound effects as a result of the teleport.)
- the destination must be known ahead of time in some fashion.
- velocity and vector cannot be changed via teleport.
- cannot fine-tune discriminate the teleport to separate mingled or composite objects, or join disparate objects.
Startup is the largest hurdle to accomplish. A poor reclusive village of monks such as you described does not have a lot of resources available with which to build up financial backing and reputation, two critical aspects needed in order to conduct business.
They have two things going for them: One, a basic first world type education. They obviously know how to read at least one modern language, and they know how to use computers, the internet, and so forth. Two, they also have a solid third world education - the ability to obtain at least a sustenance-level living in a resource poor region and still survive and reproduce. Monks or not, they have to reproduce more children with their teleportation ability, or they will all die out within a few years, unless you are proposing an unusually long lifespan, or the ability to teach this trick to anyone.
As a group of monks, they might know a combat system, many reclusive monks do. This offers the first possibility for employment.
The initial goals are to build up resources and to build up reputation. As such a few possible jobs would logically be possible for them:
- Shaolin, Ninjutsu, and other famed martial arts: Even in the modern world, Shaolin monks and ninjas have a mystique about them, a reputation which affects how everyone perceives them. If the monks have a combat system, they could build reputation in this fashion and possibly money via contests and public exhibitions, possibly also high end training for mercenary groups, bodyguards, and other protection specialists.
How do they use their power? As a martial artist, a teleportation power could be used in microshifts, resulting in the legendary afterimage effect as they dodge. If it is done swiftly enough, or for short enough distance, it might even pass observation by a high-speed camera, especially if the microshifts were only an inch or so. Make dodging bullets a real thing. Or super-jumping. This would also enable them to escape or avoid trips, holds, and locks in really bizarre ways in a pinch. Give a song and dance about cultivating 'chi' as an excuse why others can't pull off the same tricks.
- Search and Rescue: This would have possibly legal complications, depending on the country they reside in as they would have to basically barge into the profession by actually just doing it, and worry about certifications, licenses and equipment later. They might need to save someone rich and or famous in order to smooth over the minor legal technicalities.
How do they use their power? Knock everyone out and then save them from whatever natural or man-made disaster they are targeting. Maybe use some herbal amnesia concoction as part of their treatment of the rescued at first.
- Bounty hunting or mercenary work: This option is very high stakes, dangerous, and would swiftly turn into a situation where it could be tough to avoid a kill-or-be-killed situation. Depending on the target and how the laws work in a given country, even if you don't kill your target, turning the targets over to the ones who posted the bounty is the same as killing them.
How do they use their power? Catching up to marks, or extracting them from their safehouses, or possibly used to simply avoid guards, traps, and bullets.
After an initial base of funds and/or reputation has been built up, then they will be positioned to take the next step.
They are going to need to legitimize. As mentioned, they don't interview well, nor do they have any skills that stand out outside of their presumed basic education. Once they have funds, and have chosen a profession that they believe they can compete and prosper in, they will need to get educated, licensed, and certified for that work.
Assuming that they have finally built up enough resources in order to expand their operations, a few professions stand out:
No-questions-asked, high stakes, high speed, and/or diplomatic courier: This sort of courier service tends towards the, ah, "extra legal". They serve as secret channels used by governments, companies, and other (criminal) organizations for when a transaction or transport simply can't show up on the books, or be seen crossing borders. If their ethical definition is simply "we won't kill or steal", then they don't care what their clients are involved with or what their packages may contain. However, they might have to be prepared to deal with being tested with excessive force to see if they have the 'chops' needed to play with the 'big boys'. Simply dress your couriers in a full body suit of some kind to turn them into faceless legions of speed, and be prepared with lots of backup plans. The look-alike effect could also be used to advantage when faking speed via teleporting. This is possibly the most lucrative.
Import/Export/Shipping: This is tougher than it sounds due to auditing requirements (inspections, weigh stations, checkpoints, declarations, etc..) by most countries and organizations. Also, there are a lot of startup costs which would have to be made in order to look the same as any other company.
Waste Disposal: If they know of a good dead zone, they could completely dispose of things. After all, they could drop things into the planetary mantle if they could find an active volcanic shaft with a ledge that a human could survive a few seconds on. Or dump it into space when wearing a spacesuit. Either way, it's only a few miles distance one way or the other.
Blackmail and/or spying: Find the secrets without stealing or killing, then use it against those who have dirty secrets. While it may be viable as an income source depending on the nature of the various world societies, it could also be used as a startup method and/or 'clearing roadblocks' method. They could get into and out of places faster than anybody, bug rooms which have just been swept (if their timing is good), suddenly show up in order to listen in, bypass guards and other security, and so forth. This is also potentially very lucrative.
If any of the qualities I mentioned at the beginning are incorrect, then other possibilities become available.