Superheroes are not perfect. If they were their stories would be rather uninteresting. This issue is one where different superheroes would likely have different opinions and take different stances. Perhaps the conflict of opinions can lead to a very interesting story. In fact, in Batman: The Dark Knight Returns (part two), it's the political differences between Superman and Batman that lead to the "final showdown" - they're friends who don't want to fight each other, even actively avoiding the fight for some of the film, but their opinion on the role of government and their personal morality creates a situation where they have to fight. This makes the Batman v Superman fight so thrilling and engaging (unlike that other movie).
So are you being manipulated by the government to do evil? Is attacking crime, even if it comes from a broken place still good? Are you a puppet? These are questions superheroes must wrestle with - and that's the foundation for a great story!
Some opinions superheroes might have on this issue include:
- Public perception - although we might feel bad for those drug addicted, "cleaning up the streets" often improves economies, makes people feel safer in their homes, etc. Even though people in theory want those with drug issues to "get help", they don't want "those people" to be seen or heard. The attitude in many cases is "go away from me and get help". So a superhero might see themselves as giving them an ultimatum: stop causing problems for society and get help, or I'll be there to enforce the law. This helps public confidence in society to grow.
- I don't make the laws, I just enforce them. Something like Superman's "it's their world" mentality. Just because you have powers doesn't mean you can defy the government. Railroad companies in the second industrial revolution proved that: having the ability to defy the government doesn't necessarily give you the right to do so. Is it more wrong to do drugs or to defy the government? To enforce a stupid law, or to break social trust in those making the laws?
- I'll only go after dealers Sympathy is for the user, not the dealers and drug lords. Some superheros would only go after targets "higher up" in the food chain, not the purchasers.
- Defiance - refuse to enforce such laws, either quietly or loudly (ie "don't talk about it" versus "talk about it to news cameras" - both have their pros and cons).
- Get Political - recruit other superheroes to their position, use their fame to raise money for treatment plans (like many celebrities do), or so on.
There are many more approaches, but it all depends on the character of your superhero, and the world they are in.
In short, use this conflict in your story!