Here is another "modernism" that can trip people up in fantasy games.
Banking is a technology; a social technology, but a technology nonetheless. It depends on some concepts of money that grow as technology grows, and rely on a lot of social constructs that developed relatively recently in human history.
Essentially, what I see is players having trouble with banks that don't do all of these three things:
- guarantee deposits;
- pay interest;
- hold items in safety deposit boxes.
Coming from a place of safety deposit boxes, FDIC insured deposits, and banks paying interest to get you to keep moneyt with them (so they can loan it out at a proft) it's tough going to a world where:
- banks could lose all of your money and it's just gone;
- banks pay nothing to keep your money, and may in fact charge you to do so;
- don't hold items in safety deposit boxes for you.
I've cheerfully put in modern banks in games, but it's actually not something you could rely on existing in most time periods. Expecting banks to act in the interests of their customers and be reliable, safe, and money-making for the depositors and getting something quite the opposite can really throw off players trying to manage their money.
Similarly, lack of investment structures and ways to guarantee a lack of loss to your money can confound players . . . but that's a realistic problem for cash-wealthy folks in any era, and PCs often qualify.
Next time: Freely exchanged currency!