* You have to use my payment system.
* I get 30% of your gross revenue.
* You have to follow my guidelines about what you can and can't sell and how you're allowed to sell it.
* You can't, while you're at the market, advertise how customers can reach you outside the market. I'm not about to just let you use my space as an advertising channel for free.
And in this hypothetical universe my customers love it! They do all their shopping here. I can both see how businesses that don't want to follow my rules would feel super frustrated but those rules are what makes my market worth coming to. My rules basically boil down to "fuck you pay me" and treat my customers well.