[Fwirt]

Houses are big, the air mass inside is big, convection and recirculation maintain a fairly consistent temperature throughout the house, and the thermostat is centrally located so it averages the temperature of the air. The air coming out of the vents is still often colder or hotter than the set temperature, so sitting next to a vent can be less comfortable. Cars have a much smaller air mass, much poorer insulation, a thermostat that is usually installed in the ventilation rather than in the cabin where the people are, so the perceived temperature inside of a car can vary wildly if you don't live in an extremely mild climate, even as a sibling commenter mentioned, between the back seat and front seat, or between the passenger seat and driver seat.