I don't think there is any truth to this at all.
> We set a relatively low max speed
We made the mistake of mixing vehicle and pedestrian infrastructure. Our speed choices have way more to do with this than with imagined enforcement outcomes.
> because you are only going to be pulled over a fraction of the time.
Many cites engage in "zero tolerance traffic enforcement" programs. This is where they patrol a single stretch of road and stop every single person who is even 1mph above the limit.
> most are designed based on the enforcement capabilities of the time.
Most are "designed" (a.k.a rapidly created and pushed into existence) in reaction to disasters that occurred and people broadly feel could have been prevented if there was a law curtailing the behavior that led up to the accident.
We didn't make speeding laws based upon "enforcement capabilities" we made them in response to "wasteful deaths."