I think I've only every been asked for ID when buying something twice in my life and those were both in the last six years or so: both as security while test riding bicycles. Actually, might be three times. I bought two of the bikes but not the middle one. Prevalent suspicion, general carrying of ID and enforcement of minimum drinking etc ages where not yet fashionable when I was sufficiently young to suffer from them (or at least not yet in the places where I was, even though some of them had higher ages).
But I was thinking not just of hossifers of the loire and beenage hoiks. "You know you're middle aged when... " random female strangers choose to sit next to you on the bus, etc. I guess this doesn't apply if you're female.