Hmm, in my admittedly limited non-WG "dating" experience in HK, I've gone out with 5 girls (3 HK girls, 2 expat) but didn't have the unfortunate encounter you did.
4 girls (both expats, two local HK girl) offered/insisted to pay for at least part of the bill (dinner or drinks) although in 3 cases, I insisted on paying, over their friendly objections. All 4 girls were hot, with one of the local girls being very very very hot. Unfortunately, at the time, it was clear that it was just a friendly dinner/drinks without further action.
The 3rd local HK girl wasn't as hot but was decent looking, and didn't offer to pay at all. However, she did indicate (subtly at first, and less subtly later) that she was open to spending the night with me. I ultimately didn't take her up on her offer (preferred to hang out and drink with one of hot expats instead), but I might do so one of these days, as she indicated her offer has no expiration date.
These were not chance encounters at bars, but rather people I had met elsewhere, and whom I had asked out for a dinner or drink date.
Maybe we run in different social circles, but the girls I meet, even the hot ones, usually make some effort (even if it's half-hearted) to pay for something. Those who don't usually offer something else in return.