Mileage pay doesn't cause speeding but it does encourage it.
Like when you bring a straight pulloff load to a warehouse that should take 1/2 hour max to unload but you sit there for 2+ hours. Why is that? It's because the guys inside all on the clock and have no incentive to get you in-and-out. If they paid those guys by the load, you'd be outta there lickety split.
Now, I have seen a few hourly local guys speeding through slow-go zones. Maybe they're behind the 8-ball on a tight delivery cut-off? Maybe they wanna get home to momma? Maybe they're just a-holes?
But more often than not, the ones barrelling through construction sites at mach 10 are sleeper trucks.
You figure a driver at a low-ball carrier like Werner or England is gonna be making .30 cpm or less. So he's gotta bang-out over 3,000 miles just to gross $1,000 for the week. Then you've got your chicken-haulers doing multi-stop reefer work and the JIT parts-haulers for the auto companies. Those are the ones hammered down all the time speeding, boxing, tailgating, weaving, etc.
So it isn't so much mileage pay, it's the mileage pay coupled with a low .cpm and just-in-time pickup and delivery schedules. Which ultimately is a reflection of our society: we as consumers want the latest stuff on the store shelves and we want it all at everyday rock-bottom prices. If not, we'll just shop elsewhere.