Both a bank and a store involve dealing with strangers. But dealing with adult friends? Doesn't seem to hold up as an analogy, because it's issue with both the bank and the store because they don't really know you. Most people however do really know the people they game with. In fact, I bet you would not fear your friend is a potential counterfeiter.
I guess you didn't recognize the analogy, as I wouldn't necessarily fear that. (Fred Flintstone did though! You should watch that cartoon!) I would, however, fear them getting counterfeit money.
Perhaps a more common problem though, might be the issue of loaning money. If you've never seen it break up a friendship, or even severely damage one, then I would consider you quite lucky.
Take this thread for example:
totally random forum thread that came up when I was looking for the moral I've seen expressing it succintly.
There's some moral about it, but I'm blanking on it right now, so I'll just leave you with that thread.
There's many things I will do with friends. Deal with real money is not one of them. I would rather give you a present than give you a loan.
The best way to avoid problems with friends in my experience is to communicate about the actual problem if it arises, not a potential problem that may never come up.
There's a wargame tournament going on locally. It's been delayed for at least 3 weeks already. It's being delayed AGAIN because they have had so many complaints about things that went on that they feel they can't proceed until they have a meeting about it. A mandatory one. There's just too much griping for folks to be happy.
I think they would have been better off learning from the past tournaments where things like this happened, and setting the rules to avoid it. There have been people complaining about the frustration of it.
I refrained from telling them "I could have told you so" as I know that wouldn't have been productive.
Problems come up. If you head them up before they can become problems, they're usually not as bad.