Don't forget they can fight and die for our country but can't have a beer, cigarette, or a vape? That's bullThe official excuse is, 21 year olds are less likely to have 18 and 19 year old cohorts than 20 year olds. So, the 20's just get caught in the crossfire.
I said it before, I'll say it again, 18, 19, and 20 year olds can vote; hopefully they'll express their discontent over being relabeled children. If they're even aware.

Shouldn't have to sign up for Selective Service until 21...
Well, I don't believe in the draft anyway, but I digress. How can one fight for freedom when they are made to do it? Didn't have a draft in the 1st American Revolution.