Nice idea, could be expanded where you collect 5-10% of the caps a brahmin trader has paid for brahmin the same with selling slaves (to encourage the TC faction not to merely murder anyone that enters their town) and some kind of tax system where the owners collect a % of sold items value in caps (set between 0-5% by the owner faction) This way factions may find it better to let people trade in their towns and earn a steady income and if a town is known to be fairly safe to trade in because the TC faction protects it, it gets more traders and earns them more caps.
Why faction should let players trade to receive 5% or even any other % from this caps, when they can simply kill that player and receive 100% from his body?
Prostitutes: Experience (150-600)
There is 50+ NPC in every town thats impossible
Btw imagine famous trolls with negative reputation and mega AC running and killing every NPC