You're right, in that we really can't monitor much now and the bad people could be guys or girls. But at least one thing I think we know; Most of these types of crimes are committed by non-trans males. Yeah, nothing really changes as far as exposing possible new victims in the men's room but, allowing men to use the women's room does expose more potential victims IMO. I guess we just disagree if that trade off is worth making a relative small number of trans people feel a bit more comfortable using public restrooms.
Why does everyone constantly assume that the people who oppose this think that trans people are the problem. They're not. I'm not for suppressing their desire to use the facility that makes them most comfortable but I am for keeping it "out of place" for a man to enter the ladies room. Not because they might be trans but because most of these sexual assault and predatory problems are caused by non-trans males.
Anyway, I'm done because I have already stated that a dozen times. I just find it somewhat incredible that a few others don't see that we are opening Pandora's box.
RE: your first paragraph, this is kneejerk sensationalist politics/legislature at it's finest. There haven't really been studies and good research on this stuff, so why so many people are jumping to these wild solutions is just wild. However, I also don't think Target's policy is quite as loose and free as you make it out to sound.
RE: your second, it's not really an assumption, but it's a reaction to the fearmongering that IS going on. The people fighting this stuff on top, the ones with the power, are doing it by painting trans people as this phobic, dangerous, unnatural threat. Your perspective is much more reasonable and refreshing, but it's also not, I don't think, the same one being used by a lot of people with the louder voices.