That seems like an odd interpretation of supply & demand, or you mean the word easier in some other way than the work is simple/easy to do.
Because if the work is easy, and there's high demand and high salaries as a result, tons of people will flock to that easy work and the increased supply of workers would drive down wages.
They will flock but the barrier to entry is what is making supply low. It is not lack if willing workers but lack if qualified workers that makes the supply low. Obtaining qualification maybe hard or just takes too long or some other reason. Others in this thread also confuse difficulty in the entry barrier with difficulty of the work that needs to be done, these are separate things.
I am not sure we have good language for what the OP is talking about. You have hard dirty jobs that anyone can do, but there are some where there is sort of cut off that eliminates people.
Poor analogy:
The other day this lady (she was short) wanted something from the top shelf at the grocery store. She asked me to get it for her. It was easy for me, impossible for her.
