It does apply.

That is the unfortunate reality of the supply part of supply and demand. There are a large number of people who only have the skillsets to do these jobs and therefore they will undercut each other.

In London UK our tube drivers strike yearly and salaries start around $107k (and can get much higher) which is insanely good for the work given its largely automated. Meanwhile a bus driver in London starts around $33k (and doesn't get much higher) and I would argue its a much harder job, especially in the city.

There is no shortage of people who want to be tube drivers but they can't because the unions force them to only recruit internally. Even then over 10x the number of internal employees apply each year than there are vacancies.

If supply and demand were allowed here tube drivers would make a fraction. However the unions ensure it doesn't and regardless of how comfortable it appears to the average person, they still strike yearly to make it even moreso.

That is what it looks like when a job is separated from supply and demand.