So what should a candidate know to get a beginner, and upper level license?

As we are allowed to modify and homebrew equipment, we should have on
the tests questions on how such equipment works, and how to identify problem
areas like RFI, TVI, harmonic emissions and such.

Also RF safety issues, as we are allowed kilowatt levels of power.

electrical safety techniques, as much equipment use hazardous voltages
(also we should know not to wear wedding rings and such near car
batteries, a short thru a ring can burn a finger off).

Rules and regs. Like no business traffic. What constitutes malicious
interference and what is just normal life on the HF bands when conditions
are crowded.

Some knowledge of modes and bandwidth, especially why you don't
want to set your rig on 14.349 in USB mode.

Basically, we should know how not to trash the RF spectrum and
screw up other users.

What else should be here?