Safety Briefing
Here's one that absolutely slays me. This occurred to me as I was watching the BA safety video (the comedy one with all the great British actors) for about the 100th time. Don't get me wrong, it's fantastic, and I laughed a lot, at least the first dozen times.
Anyway, I just looked it up, and humans of Earth take 3.1 billion flights per year each passenger watching an aircraft safety briefing each time, for 3.1 billion viewings. If it's (conservatively) three minutes long, that's 17,682 years of people's lives spent on aircraft safety briefings, per year.
However, no one dies in aircraft accidents. Not relatively few, or virtually none. Literally NO ONE:

Airlines recorded zero accident deaths in commercial passenger jets last year. The fatal accident rate for large commercial passenger flights is one fatal accident for every 16 million flights. There were no commercial passenger jet fatalities in 2017.
You couldn't get out of the bathtub 16 million times without killing yourself. Air travel is one of the most completely and utterly safe activities imaginable. And, in the past, when there have been air crash fatalities, it's almost always the plane crashing on take-off, instantly killing everyone on board a circumstance where absolutely nothing in the safety briefing will help you in any conceivable way.
However: 1.25 million people are killed in motor vehicle crashes every year with another 20-50 million injured or disabled. (In the US, that's 37,133 dead, about 200,000 hospitalised, and 2.5 million injured badly enough to need treatment in emergency rooms. Per year.) Almost anything you do wrong behind the wheel, even for a second, can get you and everyone around you killed; there are probably at least three dozen little things you need to pay attention to and do right, or attention to which can help prevent a crash. Not one of those drivers gets a safety briefing. Ever. Maybe one in high school if they took driver's ed. (In fact, no such short, comprehensive safety briefing even exists. I know, because I tried hard to find one and ultimately had to research and write one myself.)
This system is absolutely and utterly absurd. In fact, it would be improved infinitely (literally infinitely, saving some number of lives, probably a huge number, versus saving zero lives), if everyone who flew instead got a driving safety briefing.