Why not take protection money?

I'd like it if by buying a store, you'd actually have to run it. Specifically, NOT to buy a store for $____ gold, then simply magically get $____ profit at the first of every month.

I'd rather buy the store, then have to pay taxes on it, pay a worker to man the counter, pay security if I'm having trouble with break-ins, pay a supplier for goods to stock it, or make your own stuff. Or course, if your skill is low and you stock it with low quality wares, you probably wouldn't sell much. If I was selling weapons, there would be other weapon shops in town, so I'd have to price my items competitively or I wouldn't sell anything either.

In short, I'd want it be interesting and involving with great reward if you spend time on it, little reward if you don't.