Because the title is misleading. It isn't costing 0 USD. If something costs money, be up front about it. Because a lot of people do not have much money to spend

Because the title is misleading. It isn't costing 0 USD. If something costs money, be up front about it. Because a lot of people do not have much money to spend freely, and by saying 0 USD you signal to them, only to get them disappointed later. Its a low blow, really. On the other hand, if a service is expensive, you can be reasonably sure certain types of people will not use such service. Which increases the likelihood of meeting peers of your class. Good for friendship and mating purposes. Case in point: I have fond memories of going to Playa Montroig as a young kid. One rule there was absolute silence after a certain hour. If violated repeatedly, one could get kicked from the site.