Assuming such a rule would mean "all mandatory fees are prohibited" and that we're talking about profit driven ventures (not cooperatives or patrons that might

Assuming such a rule would mean "all mandatory fees are prohibited" and that we're talking about profit driven ventures (not cooperatives or patrons that might have other reasons to want to lend money than monetary profits), you can be creative and charge money in ways that technically doesn't count as interest. The Medici bank gained lots of their money from foreign exchange speculation issuing a sort of option for buying foreign currencies at a specific date (this would probably be a lot harder to do today), you could also charge late fees with the social understanding that paying a loan back on time is really bad for your credit score. I guess a modern conglomerate might make money by putting certain terms in effect: You want to build a house but need some money to do so? I will lend you the money if you contract my contractors to build your house. A university could lend you the money but keep charging extortionate tuitions as long as the cost for the education service is unregulated.