[jazzyk]

Yes. It is the 'scalability' factor.

A star performer's pay is possible because millions of people can enjoy his/her performance at the same time, paying a relatively small amount of money (say, $80/ticket).

The software that the poster above developed can potentially be sold to a lot of customers with no extra work, so he makes an above average salary.

A teacher cannot teach millions of people at the same time, the limit is usually set at 20-25 students.

A care-provider can only take care of one person at a time, a few during the day.