I’m pretty sure someone posts a bid or an ask and then someone looking to buy crypto or sell for fiat takes them up in it.  I had sent in a “venture fund/platform improvement” idea a while back that we add an order-book in the future as a compliment to the P2P. Basically let people turn their fiat into crypto P2P and the guide them to “LCS” order-book for more high frequency trading of crypto to crypto.  Of course fees would be less there but volume would be higher.