[mytailorisrich]

Companies do pay the minimum amount they can get away with.

That said, lower paid jobs are also lower productivity jobs. There is obviously an upper limit to what a company is willing to pay that is based on productivity, and higher productivity also requires specialised skills.

No-one is going to be paid $100k to flip burgers at McDonald's both because that job does not produce anywhere near that and because it's easy to find people. If it became too difficult to find people salaries would not go very high because of the productivity cap and they'd find a way to do without people or shut down (because no-one is going to pay $100 for a Big Mac, either).

Now, they could pay a medical lawyer minimum wage if they could get away with. But the supply is quite small because it is highly skilled and productivity is very high, and so pay can be high and can remain high.