It's not that your server is trying to give you attitude--she could lose her job if she doesn't card you. A local server explains the legalities behind the "no i.d., no drink" policy.
I work as a server in a restaurant. I do not card people because I think it's fun or because I want to ruin someone's dining experience. I do it because legally, it's my job. I need to i.d. someone who appears to be under the age of 21, around 21, pretty much anyone who appears to be under 30. Why? If I serve someone who is under 21 and somehow get caught, I will be arrested at the restaurant I work at, I will face a fine, my employer faces a fine and a liqour license suspension and I will ultimately lose my job. When my fellow co-worker then serves somebody who is under 21, ( I would now be long gone and on the unemployment line, as nobody will hire me because I am now guilty of serving a minor) they face the same fines and penalties, but now my employer will have to pay a larger fine, and may lose his liquor license. A loss of his license--even suspension--is death to a restaurants business.
Police"stings" are also very common, where underage people, sometimes alone or with an older police officer posing as their parents are sent into bars and restaurants to see if we will serve them. If we do, there are again, fines and penalties.
Don't be offended if I card you. If you don't have an i.d. I can't serve you. Even if you're 50 and forgot it at home I can't serve you. And please, don't have you mommy yell at me, saying that she spent 16 hours in labor with you. No i.d. no drink. It's that simple.
When I worked as a server, I wasn't thrilled about carding people, either--I could always use those extra seconds to check on a table, refill a drink, etc. But after one of my co-workers got busted in a police sting, the restaurant was slapped with a big fine and the rest of us knew that a second infraction would be even worse. So if you want to drink, bring your i.d. Take the fact that you're getting carded as a compliment--and keep using that overnight eye cream.