Your theory is not based upon sound economics. If everyone was colluding in the way you describe to pay themselves more, then a situation would emerge where companies that didn't comply with this conspiracy would be significantly more profitable than those that did.

Note that, although managers may wish to throw money around because it's not theirs, shareholders view every penny spent on salaries as an expense that eats into their profits. They have an incentive to insist on lower employee salaries whenever possible, and they're typically the ones who make the rules in most firms.

Also, if situations like that could exist, you wouldn't only see them in the US.