I believe DL should take a lot of the blame.
So now DL must train their employees to not only look at the traveller's ID but also to do age checks??? The 10 year old travelling alone I can see DL checking, but 15 year olds these days DO NOT look 15, so are you suggesting that DL check everyone's age? Maybe they should check my ID to see if I qualify for a senior discount?
That's asking a lot of the airlines.