I don't think the comment implied that it was the "raison d'etre". A company who has employees on the road should strive to make them follow the law. If the vehicles are owned by corporation XYZ, the drivers are employed by corporation XYZ -- it stands to reason that they should ensure that laws are followed. e.g. that the drivers have valid licenses, they are authorized for employment in the region they are employed, etc. Why should following speed limits trigger this train of thought?

Yeah, but that's a little beside the point: the liability and social pressure exists (in part) for that reason, especially since without it we all kind of understand what companies like Amazon would do.

Yeah, everyone knows that these hourly workers get impossible schedules that have every moment allocated and they can't recover when something slows them down, speeding is one way to get there.

That's just companies externalizing their costs. Instead of paying for more staff + vehicles to get the job done quicker, they're externalizing the cost to the people they hit. At amazon or doordash scale, it's not a matter of if they injury or kill someone, it's a matter of how many people they will injury and kill by causing their drivers to speed.