Wannabe:"you can't blame the company if you crash but weren't wearing a seatbelt"
In todays world if you crash or go flying in turbulence without your seat belt, odds are you wont be around to blame anyone.
Cars have the light about belts, so it is feasable. Big loser is expense. When Airlines are now charging for Emergency Row seating, they certainly are not going to spend to retrofit airline seats when they have humans already on the payroll.