Because everybody's level of acceptable risk is different and adults get to choose what sort of sex they have, which is why there are providers for everybody; I don't offer OWO or RO but it's fuck all to do with me what other people do .

I'm struggling to see what their nationality has to do with anything (oh wait, it doesn't) but we're not here to comment on other people's choices so if you're really that interested in why random strangers do X, Y or Z I'd suggest emailing them to ask.

Or you could mind your own business and try worrying a bit less about what other people are doing - maybe spend a bit less time poring over other people's ads when it doesn't really serve any purpose? Either way this isn't going anywhere constructive, so I'm locking it.