Theatre prices vary enormously.
Prices are eye-watering now and I'm in the Midlands! Restricted view seats for £60!
I'm in the Midlands too, and regularly go to the theatre for under £25. I know you can pay over £50, but those aren't the so called restricted view seats, and there are plenty of seats for less, for most shows, with excellent views.
I don't think theatre has gone up - in fact, I think, in comparison with the rise in the cost of living generally, seeing shows at the theatre seems to have been a lot cheaper since covid than it ever was before.
If I compare with going to a gig, theatre is excellent value, as it is compared with some sporting events (though there is a wide variety of sporting events, just as there are a variety of theatre tickets).