Prostitution was historically outlawed because the part of the city where it happened ended up being some run-down smelly area, where you'd catch a venereal disease just by looking at it. I don't think anyone had a problem with high-class prostitutes, but it's easier to ban X than to ban poor people doing X. For example, it was only in 2009 that Rhode Island banned prostitution; but they banned brothels long before then.

Historically, it looks like the prostitution ban was mostly pushed through by this women's organization. They also did Prohibition, and this all happened around the same time women got the right to vote and WWI.

https://en.wikipedia.org/wiki/Woman%27s_Christian_Temperance...

I'm not sure how many of the historical reasons still apply: We're not in any serious war, zoning laws and city codes seem like they'd be sufficient to protect against slimy neighborhoods, there's been a 'safe sex' movement so it'd be less likely that people would freely transmit diseases, and abusive pimps don't seem as economically necessary.

Also, what's up with the VC that let a prostitute run up $60k on the tab. At no level of wealth are you ever "too busy" to watch your money, and this guy's job is to manage money.