I consider thinking to be "work".

You say that salaried people aren't paid by the hour, but that's arguably a fiction. There's always a defined work day. Some employees end up "working" for inordinate amounts of time. And some employers do push employees to be more productive.

So if the standard is 40 hours per week, I'm just saying that you do the work whenever, not eight continuous hours per day, for five days per week. That decreases control of employees by employers.