The federal law is as a FFL holder you must comply with all state and local laws if you don't you're then breaking federal law and can loose your FFL.
So the state law is you must have a FID or an LTC to buy ammo so technically you as the FFL holder must ask when you see that out of state drivers licence.
And yes the actual federal law on ammo if 18 rifle 21 hand gun ammo and that your not a prohibited person.
And yes again they can totally skip on asking for a drivers licence if you look old enough bit once they do ask for the drivers licence and your out of state they are technically supposed to then ask for your FID or LTC.
But come on you all ready know that don't you have a FFL.
The reason you are wrong here is that the Feds do NOT require one to have an FFL to sell ammo!!! Some states require it, but it is not a federally controlled object wrt sales (neither are magazines).
Maybe, but the store POS system might require ID info for every ammo sale. For instance, if you purchase liquor at say Target or Costco, the cashier is required to scan your license regardless off how old you look. The sale cannot be completed, the transaction won't make it through the computer without the data from the license getting entered. This requirement is made by the store, not the state.
Don't know about walmart, but possibly they have a system like this setup where to complete an ammo sale, info , possibly just DOB, MUST be entered?
Sorry, you are wrong wrt Costco (same with BJ's and Sam's Club) and booze. I've bought liquor many times there in MA and NH and never been carded. Clerk just looks at me, yup he's old enough, and hits one key to pass.