Not quite, not using a condom you may not pick something up for several months but you will eventually. I've told a couple of girls i got an STI from them told them what they need to take but they just deny it, so i gave up telling them, anyway since using Doxy PEP it's not been an issue
Guys are also taking PrEP which isn't an antibiotic, taken in advance of sex and gives very good protection against HIV, can be taken long term or just holidays, weekends, whatever
Yes, the trick is, same cash, get it ready before you have to pay, for a meal or coffee i will often scan and pay during eating/drinking, at checkout i login to bank app, finger print etc in advance