Many other countries are on the whole much less puritan than the US. You mentioned Latin American countires. Well, in Brazil its  extremely easy to have casual sex without paying. Because the process of selecting a partner is mutual. Girls there don't select you and then you have to jump through hoops and gps maze.  

 
You meet a girl, she likes you, you like her, boom. She's down to fuck. Because she also wants to fuck and doesn't feel the need to do a thorough selection.  She spends the night or few hours with you, has fun, then to the next one.  

 
And in such countries p2p is also easy because it's not looked down upon and there's no stigma. If anything, the western world views sex as something sacred and something that should be kept under wraps. Many other countries view sex as a fun activity where most people participate and there isn't some selection.  

It's not common to find people with 20+ sexual partners here unless you p2p or a playboy/playgirl. It's common to find such people in many other countries.

80% of the women chase 20% of the men.  That's the civie situation.  If some guy is bragging how easy it is to get laid whenever he wants, either he is lying or has good looks.  This is especially true of guys still in their 20's.  Once men are established in their 30's and beyond then the aging out women who never could land the cute guys will be more acceptable of hooking up with a guy that is financially sound, even if she doesn't find him "hot."  
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P2P is an outlet for these (we) guys.  At least we can have sex if we can come up with a few greenbacks.  Hopefully enough so that we don't have to wife up later in life with the chicks who are just looking for a provider.