Is this really a ubiquitous thing in the US? Office jobs were you are paid for having your body present, regardless of whether you slack off most of the time?

Is this really a ubiquitous thing in the US? Office jobs were you are paid for having your body present, regardless of whether you slack off most of the time? Who pays for this? Isn't it terribly inefficient? I mean, if there's just not a lot of work to do, you could also have shorter work weeks. And you would, if your boss could trust you to not slack off every time they turn their backs? Wouldn't it be more logical to do your work and then have actual time off, instead of pretending the work takes much longer than it actually does?