I'm not sure this is anything new though. Even before Venmo, I've always had friends who were overly concerned with keeping things "even" between us and friends

I'm not sure this is anything new though. Even before Venmo, I've always had friends who were overly concerned with keeping things "even" between us and friends who were very loose with money and wouldn't mind spotting me $20 with no immediate expectation of repayment. It's one of those social things that really depends on the history, social norms, income...etc of those involved. I try to just go with whatever makes people comfortable without thinking about it too much. And for friends I already have a set of expectations. Also, beer example was just meant to highlight that friend we all have who practices "selective accounting" with our informal running tab. If I had any suspicion that $3 is make or break to someone I would gladly pay them what's owed and forget about the beer. Beer (and all vices really) have their own set of norms.