Rarely did. I was briefly legal at 18, legal for 6 days at 19, then had to wait two years. However no one really cared back then.
About 10 years ago I got carded at a baseball game. Even worse that’s when I found out my drivers license expired, so they wouldn’t sell me a beer despite my obviously being well over. To get some amusement out of the fiasco, I slipped my 21 year old coworker a $10 to buy me a beer
Cashiers used to be able to use their judgement and not ask for ID if the customer appeared to be older than 27. But I guess there was some abuse of that, so now they card you even if you're clearly 100. The ABC (alcoholic beverage commission) will even sometimes do stings to see if the cashier asks for ID, and stores can even lose their license to sell alcoholic beverages if they get caught.
When I worked in retail locations that sold alcohol and tobacco, the official policy was that you didn't have to ask for ID if the customer appeared to be older than 40. That was 20+ years ago, though, and it's possibly a regional or company-specific thing.
These days, it seems like most cashiers at most places that I shop have a blanket policy to check ID and enter it into the register regardless of the customer's age. So, I'm thinking that their training is leaning heavily towards scaring them into IDing everyone. It's a legit concern, though. The alcohol enforcement stuff is serious and some of the people doing that job will try to trick cashiers.
Your experience reminds me of my own: When I was younger, I rarely got carded. Now that I'm well above the legal age, my ID is checked much more consistently and frequently.
A lot of places ask anyone and everyone to provide ID which I don't think was the case in years past. My wife and I are 40 and we still get carded frequently and I don't think it's because we look underage.
I always pull it out and stick it on top of the alcohol so they never have an opportunity not to ask. They can get in trouble for not checking id (or they can in my state) so its kinda a polite thing to do.
In my hometown, which has a large state university, they ask everyone no matter what age. Moved to a city about an hour away where there is a small university around age 23 and have never been asked for ID there.
I look older than I am. Didn't start buying the stuff until I was 21 and never been asked for my id to buy it. But I have been asked when buying cigarettes so make that make sense.
I live near a college town and closer to it, everyone gets carded all the time. Some places must have not done even that well enough because at some places you had to have your id scanned or sign a log swearing it is, in fact, your id.
I have only bought alcohol legally one time. It was at a burlesque show and it was for the MC who was a friend and forgot their money. I was in my late 30s and was not carded.