Re: If you want puritianism then
Illegal even to have a closed but opened bottle (i.e. a bit has been drunk) in a car even if it is in the trunk
Most states specifically allow an opened bottle in the trunk or space other than the passenger compartment. It's only a few of the more authoritarian states that word it ambiguously which would ensnare folks.
Cali is one of the worst since it allows "any person who has purchased and partially consumed a bottle of wine to remove the partially consumed bottle from the premises upon departure" yet also says no driver or passenger "shall have in his or her possession... any bottle, can, or other receptacle containing any alcoholic beverage that has been opened or a seal broken, or the contents of which have been partially removed." Typically items in the trunk are deemed to be in the possession of the driver so while they're ok with you taking what's left of the wine bottle from the restaurant you have to have someone walk it home.