A lot of people on this thread, and the original 'Biggin crash' one, seem to think that anyone with enough money can take part in an air display. Wrong!
You need a CAA Display Authorisation before you can take part in a display, and the people who decide whether a pilot is up to the job know what they're doing.
That's much more effective than the show organisers (who may not be even Cessna-PPLs assessing if the pilot's got got enough experience either in total or on type.
As for P51's careering off into the crowd. There isn't now, and never has been, a problem with P51's or any other type of warbird, careering off into the crowd. Doesn't that tell us that somebody must be doing something right?
Reading the two threads, I can't help feeling that some (I say again, some) of the contributors making assumptions, comments and suggestions about the system don't know much if anything about what actually goes on in the airshow world, particularly the warbirds side of things. Perhaps I'm wrong.
(PS I'm not saying I know that much myself. I don't.)