I don't believe it's some work ethic that is at issue. It is a 'if your ass isn't in the seat you're not making me money.' It's the same reason sick time in the US is so low, why vacation time in the US is so low, why showing up on time is so god damn important and why any activity that isn't making you or your employer money is looked down upon as a waste of time.
In many ways, the US economy never grew out of the slave labor mentality.
This is a matter of not wasting other people's time, it is a matter of respect. If you prioritize and plan accordingly, being prompt is usually quite easy. If you haven't done so, then you are effectively saying that your laziness is more important than your compatriot's time. Of course, this is only important when one of the parties has this view (it is some sort of prisoner's dilema, I think.)
I’m having trouble trying to find an instance of people not waiting on you at work (any work). Either it's real work with real consequences or it's busy work.
The thing is that there is plenty of work that isn't due on a tight deadline right now, but takes time to do. In these cases, why should my boss care if I decide to work noon to 8pm instead of 9 to 5? My boss doesn't care. I am my boss.
The measure of a good knowledge worker though is not being on time, rather it is productivity month over month.
It really depends on how much coordination is needed on a daily basis, I think. In tech especially there are a reasonable number of companies that are fairly lax on caring what precise hours you keep, so long as the git pushes and bug triage keep coming.
In many ways, the US economy never grew out of the slave labor mentality.