So under that sweeping generalization, you consider rape and murder equivalent to, say, coming out as homosexual??
Reform is necessary, but you can't just boil everything down into apologetics of "institutional discrimination against the morally-impaired."
Its political, and at least in the US, it traces its roots back to corruption and how unrepresentative the US government is of its citizens.
If you want to fix almost all societal problems, you first need a system of government that fears and respects its people. I don't care which permutation of state you pick, but if you want a government to care what you say, it has to care about its people.
Most countries have that problem. Its less overbearing because most European states have better implementations of near the same parliamentary system, but even those governments are often too centralized and too easily corrupted, and that breeds an unrepresentative state.
Making a government that acts in the will of its people is absolutely step one to fixing the problems it causes. Then you just need to persuade the people and thus the representatives to change it.
I am fundamentally opposed to prison in all but the most extreme cases. I also happen to believe a bunch of other things that would also see me branded as a radical by society, but I digress. Prison is fundamentally destructive as an institution. It is slavery by another name and it must be dismantled, though I don't know how we begin the process.