Because marginalized individuals are living their lives in a public space, they're constantly under police surveillance. This is a real issue for sex workers, who are trying to make a living working on the street.
They are targeted for police harassment for a number of different issues, such as maybe earning money in other ways, such as street vending and other such activities that are often criminalized by the police. They are sometimes working in circumstances of homelessness and sometimes trading sex for a place to stay or things like that.
The law certainly doesn't help with some of the issues that marginalized people have to face on a daily basis.