I was over in San Francisco last summer and walked out of a bar pint in hand to tag along for a cigarette break, we were promptly chastised about it. I apologized saying that I'd briefly forgotten what continent I was on.
It's also not unusual to see children milling around with their parents in bars in Europe well into the evening. There's no demand that you have to be of drinking age to be in the establishment, just that you can't be sold drinks if that's not the case.
All in all it contributes to a more relaxed atmosphere around drinking and I suspect to overall moderation and safety around drinking.
If you ban guns in bars then someone who carries a gun around anyway will have to stash it somewhere before they arrive, or risk breaking the law.
I carry a swiss army knife on my keychain because it's a useful tool, I bring that to bars I go to. I don't think I'm any more likely to attempt to stab someone after a few pints than I otherwise would.
Still, I totally agree with you. The stringent attitude towards alcohol-serving in the United States does stigmatize it's consumption quite a bit, and, IMO, causes a decrease in moderation and safety when compared to a more relaxed Europe.
edit:spelling
Coat check for guns? A peace tie (zip-tie) on the holster? It's not like this isn't a well understood problem.
Make what you will of those arguments, but note both options could also be applied to car keys of people entering a bar (check your keys so we can evaluate your intoxication before giving them back). In fact, one could note that cars are a tool much much more often used by the intoxicated to murder (commit manslaughter, if you like).