The problem is, its still the same... Those women did not get into prostitution willingly. So their handler/pimp/illegal traders are just as illegal now, then under a legal system.

You understand the issue? Legal drugs does not mean there is no more illegal sales because they do not pay taxes etc, so it still exists. And is still illegal. But the punishment before or after legalization, is still the same for those doing the illegal things.

How can a illegal prostitution still exist? Cheaper prices because the people being forced into it are not doing so from themselves. Aka slavery is cheaper then legal work.

A solution is heavier punishment for the pimps / human traders etc. But non for the victims! What unfortunately still happens in countries where prostitutions is illegal, thus creating a cycle that victims do not go to the police, out of fear of ending in jail themselves.

Even if you make prostitution legal, the people who do this without paying taxes / registration etc (aka people victimized) are doing a "black job", what again opens themselves up to fear for the police.

There is no easy solution for the problem of illegality (willing or forced) or else it will have been solved 1000's of years ago.