The sickest industry

What is a sick industry? According my definition, an industry where people are not really paid what they are worth. Of course there will always be people, who can sell themselves better than others in all industries. But I recently spoke to a good friend of mine and she is constantly struggling income wise. Her profession? She is a Concert Pianist. Concert Pianist means two graduate studies at University level. First the Diploma as a professional Musician, which is literally a Masters Degree and then four more years of studies to get the Concert diploma. And she has to teach pupils for an hourly price that makes me laugh and cry at the same time. 8 years of Music Academy drill and she works for HALF the price as for example the gardener who overhauls my garden twice a year. HALF the price as the painter who recently painted 3 walls in my house.
This is crazy. Would somebody who studied law ever work for that price? An engineer? And more importantly: Would people EXPECT a lawyer to be that cheap? I don't think so. On the other hand people are prepared to pay 250 Dollars for a ticket so see Barbara Streisand. But when people want their kid to learn the piano, they think it must be dirt cheap. I don't understand and it makes me a bit sad...