Isn't this exactly what some parts of the rail industry do?
They tell you the theoretical maximum (the walk-up standard class Anytime ticket) and then set the mandatory reservations flag and pretend the ticket is unavailable/invalid for a specific busy train (despite being available at ticket offices/TVMs and the tickets being perfectly valid for travel). Retailers then flog first class advances / first class walk-ups, because they're the only things with quota left (all the while the quotas at each price point are being adjusted dynamically by a computer according to demand), and the customer overpays accordingly.
I fail to see the difference! Except of course that in one instance it's a government controlled operator doing it, and in the other case it's a private company.
There's a lot of difference between an event that keeps some entertained for a few hours and a transport system that may carry people who
need to get from A to B. Being unable to afford a ticket (or get one at
any price) to enable people them to access a venue to hear and watch a music event*, bears no comparison to a person who cannot get to work/attend a hospital appointment etc..
* also true for any other restricted availability 'entertainment event including more formal music, plays, ballet, non-participant sport etc..