Not only that, some people leap to the conclusion that you don't drink because you're an alcoholic, and from there to the judgement that you're unreliable and untrustworthy. (Not that being an alcoholic makes you those things - but that's their perception learned from our culture.)
Another unhealthy thing about drinking culture is how it stigmatises teetotallers as some moralising oppressers (thanks Prohibition), when they might just not want to feel like shit in the morning.
Maybe you're driving. Maybe you're on medication. Maybe if you're a woman you're trying to get pregnant (or already are).
Either this "if you don't drink you must be an alcoholic" thing is entirely American or lots of people on HN hang around with the wrong crowd.
EDIT: Also being "on call" is a good reason not to drink. Though if you need an excuse every time you go out with your friends, you deserve better friends.
I'm in rural Germany. For 20-somethings it's perfectly normal to have designated drivers who don't drink, no questions asked. If you're a woman, most people will suspect you're pregnant but it's too early to be socially acceptable to ask you about it.
Transportation plays a larger role in determining "tolerance" for how socially acceptable that is. Urban environments, with their preponderance of cars for hire reduces the need for designated drivers.
I live in a suburban area in the U.S. and what you report is similar to what I've experienced, too.
It could also be that my social circle is older, and many of us are parents, so it's not as convenient to go out for a hard night's drinking.
Yeah, with friends who are parents the designated driver of the two also usually is the one who has to take care of the kid (especially when it's a very young kid).
But even when I'm out in town non-drinkers aren't bullied into drinking. If it's a party and they're not drinking (especially if they're men and thus pregnancy is off the table) someone will likely push them on it because it's uncommon but no more than vegetarians or anyone else with dietary restrictions.
However in that case "I don't drink because I don't like being drunk" or "I don't drink because I don't take it well" is a perfectly acceptable answer. Then again, a lot of the people I'm talking about are goths so straight edge / clean living isn't too uncommon.
Another unhealthy thing about drinking culture is how it stigmatises teetotallers as some moralising oppressers (thanks Prohibition), when they might just not want to feel like shit in the morning.