They are a for-profit production. Their goal isn't to get the public to see theatre, like say, the PUBLIC theater.
We can talk all about the merits of government-supported, public theatre, which is much more common in the UK and other countries and I happen to think it's phenomenal, but this is not a "public" show.
The show does offer rush for EVERY performance and SRO so it's not like it's impossible to get an affordable ticket if you're really dedicated to it. The ability to raise ticket prices and make profit are the reasons we have private theatre. If the government won't be sponsoring the arts (and it seems like that's becoming even less common,) we have few alternatives other than to accept and enjoy private theatre.
Scratch and claw for every day you're worth!
Make them drag you screaming from life, keep dreaming
You'll live forever here on earth.