Memes

The assumption here being that we live in scarcity?

This isn't an assumption, this is objective fact, we don't have infinite resources.

That worker productivity is directly tied to the amount of time worked?

It's not 1:1, but there's a strong correlation between productivity and time. Obviously having workers work 16 hours a day is not going to go well in terms of productivity, but a person who works 6 months of the year and a person who works 10 months of the year are not going to have the same annual productivity. The person who worked for 10 months is going to be more productive because they put in more time.

That people won’t take difficult jobs like being a doctor without the financial incentive?

What's the mystery here? Money is indeed a big incentive. Why would anybody spend about 14 years of their life after high school studying very difficult subjects to work very demanding jobs if they end getting paid as much as a delivery driver? Might as well become a delivery driver and save your save a decade and a half of stress.