You’re looking at this as an economics issue. But I think it’s a fundamentally a biological or evolutionary artifact. Evolutionary biology has intraspecific competition for access to mates to mating opportunities as a driver for change.
Organisms work to prevent the resource from being exploited just like water, habitats, space, etc. It’s other women that would lose if access to mating opportunities are tied with monetary transactions, and a few would benefit. Minimizing prostitution helps the female of the species be more selective about their mates, and increases the “value” of their interactions.