because otherwise the shareholders eat you alive for not chasing infinite profits.

I think that while the threat is real, the threat being a major motivator for upper management is largely illusory. It's absolutely there, but it's not making them do stuff they're not already keen on doing. Nobody weasels their way up the ladder to do non-profit-maximizing things, occasionally getting reprimanded for not maximizing profit and always one stray "the old phone's fine" tweet away from getting canned. They're willing and enthusiastic profit-maximizers.