I'm somewhat distantly familiar with a British opera company. The usual rule is to do one or two mainstream bums-on-seats shows which are more or less guaranteed to be successful, and then fill in with less standard repertoire around the edges.
So sell out shows do happen, at more or less standard prices that are surprisingly affordable, and much less than big name pop artists charge for their tickets. But the sell out shows are more or less at capacity. There certainly aren't thousands of people willing to pay five times as much for a seat.
And in fact there is absolutely no way that income from ticket sales would be enough to keep the company running.
The rest of the money comes from sponsors and from Arts Council funding. Getting money from both is a highly skilled full-time job.
This company happens to be very good at fundraising, which is why they still exist. (Actually they're very good at everything, not least the artistic side.)
Would on-demand pricing work? Absolutely not. The audience is older and fairly faithful, and they tend to feel they have a personal relationship of sorts with the company.
Variable on-demand ticket pricing would completely destroy that relationship, and I would be hugely surprised if it didn't also make sponsors feel like less like contributing.
