Humans are very good at optimizing their behavior for close to constant risk. If one party does stuff to increase safety to compensate for other parties not being alert as they should be then the other parties will decrease their alertness to keep risk constant. You give them blind spot detection that works most of the time and they merge onto a motorcycle because they've learned to stop looking. You put orange barrels up at 99% of the road hazards and they'll drive right into the one that doesn't have them because they expect there to be orange barrels. You remove the little holder tab from gas pumps and people just shove the gas cap in (it fits perfectly). You put emergency stops, fail-safes and limit switches on power tools and they become part of normally operating the tool (why disengage the blade on a riding lawnmower when you can just take your butt off the seat and it will do it for you, no reason to not overload the trash compactor when it's got a relief valve).

Once you get beyond the bare minimum of warnings that alert people to some hazard returns diminish quickly, better to spend your resources on minimizing the damage of people being dumb than preventing them from being dumb in the first place.