But I'm not sure I understand your point. It seems when large vehicles stop suddenly, unsecured cargo doesn't. Airplanes have them don't they? I had heard so

But I'm not sure I understand your point. It seems when large vehicles stop suddenly, unsecured cargo doesn't. Airplanes have them don't they? I had heard something suggesting seat belts are not cost effective on trains and buses for the amount of lives saved. Perhaps that's what you're thinking of. Still, I would rather have them even if it cost an additional tenth of a cent per mile.