The world would remain (mostly) unchanged thanks to Maslow's Hierarchy of Needs.
People who could photosynthesise (and therefore not require food would have a dramatic impact on the global industry to be sure, but the one thing that would NOT happen is that people stop working. Many industries, like farming, would not exist but people would find other things to do, just the same as in Star Trek (a model for a post-scarcity society) people still continue to work, do jobs and sometimes deal with bosses they don't particularly like. Why? Because food (like shelter, oxygen, water, etc.) is only important to people when they don't have any. When they do, they move on from that onto other things that concern them.
This is true even today; as an experiment, check your monthly bank statement. Read off what you made for the month, and what you spent. Take away the food bills. There is still money you've spent of your paycheck. What was it on? That is the answer to why people would work. Whatever that difference is, that is why you work - to get more of that.
This is where Maslow comes into play. The truth is that the pyramid in the link is foundational in nature; that is to say, if the bottom bit is completely covered, you focus on the next tier up. If that is covered, you focus on the next, and so on. Your focus remains on the lowest tier which is not completely covered by your situation.
So, let's say that we don't photsynthesise, but that food, shelter, clean air and water, etc. is so abundant that you have access to all you want or need of any of it. Let's say that this abundance makes you feel completely safe and you have the love and respect of your family and community. All that makes you feel good about who you are and what you do in your life; what is left? Why work after that?
Because you will want to extend yourself; that's why. You'll want to learn new things, be good at something you really care about, make the world a better place, extend yourself so you can feel enriched by the process of becoming better than you are.
Ultimately, food is such a small component of what drives me personally to work that it's not funny. I work to make the world a better place, but then I'm one of the lucky ones who can say that I'm that far up the hierarchy. But, if you take food out of the equation, Maslow provides a handy reference of all the other things people will worry about and work at jobs to provide for in their life, all the way up to making themselves the best version of themselves they can possibly be.