This! The reason milk isn’t “socially acceptable” to drink around in public is because milk isn’t really something that is commonly in a portable form factor. If you see someone drinking a milk carton in public it’s no different than seeing someone drink a juice box or a can of soda, or a can of beer. Except milk cartons aren’t really too commonly available at any gas station.
The most uplifting comment you’ll ever hear out of a Bostonian