The way I see it the seatbelt law came about like the "Third" brake light law. A law created to fix a non-existent or overblown issue. IIRC one of the reasons given for the need for a 3rd brake light came about because insurance companies and "Safety Boards" showed satistical evidence of high rates of rear end collisions and the excuse was "I didnt see their brake lights" instead the real reason, "I wasnt paying attention" (I might be mis-remembering)
I dont think having a 3rd brake light is bad, heck it gives you an extra light when the others ones burn out...we just didnt need a law for it. Or for the stupid seatbelt light and dingers...or nutrition lables on bags of chips and bottles of beer...
And last night I let my son drive and I rode in the back seat, and yes those are uncomfortable