Today I went with my dad grocery shopping at a supermarket in New York (ShopRite) and he put a six-pack of beer in the cart.
They then wouldn’t let him buy the beer because they couldn’t ID me (21, but I dress for work so I look more like 25). Even when I left the store to wait in the car they made him check out at a different register.
Is this legal? I wasn’t buying anything; I was just helping him load stuff onto the conveyor belt.
It is legal, at least in the US, for a store (or other entity) to refuse to sell any item to any individual for any non-prohibited reason (prohibited reasons are typically things like race or religion).
More over, in various US jurisdictions, it is prohibited to "furnish" alcohol to a "minor" (for example, under California's ABC law), which can be interpreted as prohibiting to an adult if they reasonably suspect that adult will pass the alcohol onto the "minor". This is to prevent "straw" sales.
Additionally, larger chains generally prefer to have harmonized policies across branches, and where practical, across state lines, so will have policies that can accomodate multiple alcohol control regimes.
You go into a store, pick up an item, go to the counter and you think you are legally entitled to own the item provided that you pay for it? Wrong. Wrong for any item, not just alcohol.
Items that are on the shelves in stores are not offers in terms of contract law. They are invitations to treat/bargain. When you take an item to the counter it is you who makes an offer to pay for it. And the store is free to accept or reject your offer.
The answers here are already correct, but wanted to make a quick comment over this
Even when I left the store to wait in the car they made him check out at a different register.
It is of course completely silly that this is required, but from what I was told when I worked at a liquor store this was needed. The idea is by checking out at a different register with a different cashier it passes liability over to the customer if anything bad was happening. The original cashier already knows that Person A came in with Person B who could not be properly ID'd, so even if Person B leaves, OG Cashier is obligated to refuse sales to Person A. Switching over to a new lane meant Person A was now in a 'new' interaction with New Cashier who has no knowledge of Person B and would not be knowingly making 'straw sales' as @sharur mentioned.
Things always got interesting when the adult got annoyed with their 'kid' for wasting more of their time and said they are charging them more. And then they got really confused when we refused any further sales at all....
It's not just legal, but often (depending on the state/county) legally required, otherwise they would be considered 'negligent' in helping providing a minor with alcohol, which can get them in jail.
