You don't eat all the ice cream in one sitting. If this random ice cream[1] is an indication, serving size is half a cup, so a half gallon should provide 16 servings. If you like the flavor, why not buy 16 servings at a time; if you live in a household with four people, that's 4 sittings of ice cream.
In the UK I don't think even the largest ice cream comes in more than 1 litre. Most is around 0.5 litres. And even that for a family seems like a hell of a lot of ice cream. One litre is a crazy party volume of ice cream. A half-gallon sounds absolutely bonkers.
Of course, with as much air as comes in the ice cream here, a half gallon is probably only a liter of actual ice cream. They definitely don't weigh nearly as much as they look like they should.
You need air in the ice cream. Ice cream without air is frozen flavored cream and you'd need tools more substantial than an ice cream scoop to serve it. The manufacture will vary the air content to dial in a particular hardness.
Ice cream in Australia is available in 4L tubs down to smaller tubs for premium brands or more exotic flavours. Doesn't seem excessive given it (ideally) takes over a week to get through.
[1] https://www.target.com/p/breyers-original-ice-cream-natural-...