A lot of this is reckless sexual behaviour. It's incredibly frustrating, because one of the medications used to treat syphilis is now in short demand globally. This medication is also used to treat other (potentially fatal) infections. In other words, through no fault of their own people will (or likely already have) died due to people not practising safe sex.
It's easy to blame people on tinder, but sex education and poor healthcare are just as much to blame.
For example, syphillis is often spread orally. I don't know many people who would wear a condom to give someone a BJ, even if it's a random hookup with someone whose sexual history they don't know.