Question about buying beer?

I used to sell motor oil to a small town energy distributor who also owned about a half dozen C-stores. He got both the wholesale and retail mark ups on the gas sold at the stores. A good racket.
I asked the owner what the deal was with the age proofing on old guys like me. He said it was strictly for liability. Every alcohol customer is on camera, showing his ID to the clerk. No one will likely win a lawsuit blaming them for selling to underaged kids, and for what damage they may do under the influence. He also gets an insurance discount for enforcing the policy.