It's a weird cultural thing
Not using a seatbelt was the norm only fifty years ago.
Not sure how many road trips you took as a child, but lying down across the back seat with a seat belt is harder than without.
We used to just throw caution to the wind, put the seats down in our suburban and fill the area with blankets.
Seatbelts save lives, it's a fact you can't get around. When they developed and tried them, they realized how good seatbelts are and decided that every car should have them, not patent fee for any manufacturer.
Or just don't buy an electric car...
Someone I know has a brother who was in an accident, was wearing seat belt, was stuck in the car as he couldn't release the belt, and was burned somewhat. He simply couldn't buckle up after that and eventually got some kind of exemption for medical reasons.
https://www.amazon.co.uk/AA-Emergency-Windcsreen-Hammer-Seat...
I don't even recall ever thinking that as a child passenger.