We "speed" because speed limits are used not as a tool for defining normative behavior and policing rare outliers, but rather as feel good social engineering - similar to the war on drug users. Note how that AAA's article definition of unsafe wholly depends on what roads have been
signed.
There's a stretch of through road around me that had been signed a low 30 my whole life - straight with perfect visibility, sidewalks, decent house setbacks, backyards for most activities, etc. The prevailing speed is 40 (adding 10 is standard and accepted around here). I've never seen or heard of any kind of crash on it.
I tended to keep it to 35 because my parents were always complaining about getting tickets on it [0], and as I got older I decided it wasn't worth worrying about (I would generally end up being tailgated for this). But recently, the city ratcheted it down further to a ridiculous 25 [1]. Since the customary speed is now so far over the sign I've just given up and go 40-45 now while spending the effort to scan for cops.
[0] in retrospect I think they were just unobservant, since there's nowhere really for a cop to hide. I've only ever seen cops sit in one place, and it might as well have a big red arrow pointing at it
[1] along with a lot of other roads, I think they must have gotten a quantity break on the signs. Or maybe just a bad case of affluenza.