"approaching women outside the permitted times, not approaching women outside the mandated area, outside businesses etc?"
Kerb crawling is illegal I think but many women have been kerb crawled just generally, I have been offered money for sex more than once, just in general life. In areas like this (my friend went to uni in Leeds and lived in a place with a lot of street prostitution) it's just a daily thing that you get.
While kerk crawling is illegal I dont' know how many actually report it and what the police would do if you did. Most women I think just put up with this sort of stuff, while feeling angry about it, at least they did when we were young.
The other thing is like in general life, there is no context to who they ask, as with non prostitute woman talking activities, men just seem to take a scatter-gun "no harm in asking" approach. Hence you get men kerb crawling / approaching generally, schoolgirls, women with children, heavily pregnant women etc. The men don't look for any clues as to whether she will be receptive to what they are asking for, they just register "female - can see tits. got a good selection of holes" and go and see what they can get.
I think for men, who presumably don't get these kind of approaches, they can't (can't be bothered to) understand why these kind of approaches are intimidating, unsettling, dehumanising. The response is that if you dont' want to be approached by random men for sex when you're out and about, you must think there is something "wrong" with being a prostitute and you're "whorephobic". This is something I have seen on libfem boards as well. Only the very hard of thinking can't understand why it's not good and adds to the weight of street harassment.