But it's not as bad as it is today when sex trade has been linked to the spread of certain diseases.

The situation is only made worse by illegalization. It means that it's harder for them to get healthcare, or to seek the help of the law.

https://prostitution.procon.org/view.answers.php?questionID=000107

That site covers whether or not the incidence of STD's would be lowered with legalization. The cons have mostly to do with one particular option, a test card, which they point out is pretty much useless.

It's easy for a lot of people to say can't they get a better job?

Put another way, sometimes it's the best job available. Good pay. Flexible hours.

Uh.. not everyone is privileged enough to have gone to school or have connections.

Sex workers aren't even always uneducated. In America, some of them are even highly educated.

We have this view of sex work as dirty, and the sex workers as poor people whose only option is the sex trade. Reality is often far different than the visions we paint. In this case, that vision is based on our prejudice.

But condemn them or not, we should not condemn the children.

I find it interesting that I can't seem to recall any charity event targeting that sector in our society.

I don't think they even necessarily need one targeting them. Just one that isn't discriminatory.