I would argue that if what the employer expects to be done in 40 hours can be done in 20 by a skilled employee, then it’s not exactly the employee’s job to tell

I would argue that if what the employer expects to be done in 40 hours can be done in 20 by a skilled employee, then it’s not exactly the employee’s job to tell them to allocate more work on his/her plate for the same amount of pay. That business needs to do a better job of understanding the work they need done. This, of course, won’t apply to a job like a call center or something where the time on the job is itself the labor being done, only in cases where the output is measurable. But in those cases, the employer’s feeling cheated by not being able to waste the time of/underpay that skilled employee doesn’t exactly sadden me.