I'll tell you dear Quentin, why it's needed.
It's needed because even among the non-sex worker girls contingent in Thailand, the "good" girls who don't sell sex directly, even they, believe it or not, will have opened their legs for on average 6 to 10 guys, of whom at least 2 or 3 were in fact Russians, Israelis, Arabs or Ukrainians using prostitutes and thus could have infected these non-professional girls. Without them even knowing often, so they can't even warn you.
It's shocking how much sex girls are having before they meet you, even those in their early 20s. Shocking I tell you.
And when they tell you you will be having sex with all the people she had sex with before, that's not actually joke. That's more real than we'd like to believe.