The amount a certain job pays should depent on anything but the effort it takes. Otherwise it would incentivise to never innovate and improve methods.

Why should one invent a weaving machine if doing it by hand is so much more difficult and would pay so much more?
Why should we invent the printing press if spending days copying a book by hand is so much more effort and pays better?
Why do we need cranes if carrying bricks up the hill requiers more work and therefore pays better?

We would basicaly still be in the stone age.

The way it works in our reality is, jobs that a lot of people are willing to do and that require the least amount of training pay little, jobs that only a few are able to do and require a lot of training or eduction pay more.
On top of that, its also a matter of responsibility and liability. If you miss a spot during cleanup as a maid, its no biggie. If you hit an artery during operation as a doctor its life or dead.
And on top of that its partially the employers financial risk and reward in taking you on. A cashier is trained easily and is highly replacable. Their work will generate value for the employer basically on the same day that they start but it’s very limited. If they screw up, they can be let go without further thought about replacement. An engineer will on average start generating profits after roughly 2 years of employment, but those potential profits are a lot higher. This means that the employer has to keep the engineer incetivised to stay with a higher initial salary, to not lose their investment.

As an extra, specialized jobs that require little education but only a few people are willing to do can pay more than they usually would. Nightshifts, working on ships or drill rigs, etc.