[adrianN]

I think with "difficult" he didn't mean how physically taxing it is, but how hard it is to find people who can do it. Almost anybody can to the work in a sweat shop after a couple of days (weeks?) of training. Becoming a programmer is not something everybody can do and even for those who can it takes years of study before they are competitive on the job market.

[xorcist]

That's not the complete truth either. Where I live there has been a nurse shortage for a long time, but they're not paid better anyway.

Before you say education, some specialist nurses have almost as much education as doctors. They don't receive close to the same pay.

Most of the answer is cultural expectations.