I highly doubt you’ve heard a sonic boom at an airshow, it’s illegal to perform them and has been for a long time. A true sonic boom performed at low altitude at an airshow would blow out the eardrums of every attendant at the show and all the windows in every car in the parking lot. Only the military is allowed to cause them and only for very good reason. There was a recent case in the UK where fighter jets caused a sonic boom as they were scrambled to respond to a malfunctioning plane; the video is here https://m.youtube.com/watch?v=fGR96Zz0dXk and it had people from over 20km away calling the police to report that a bomb had gone off somewhere nearby.
What you’ve heard at airshows is close to a sonic boom, it’s called “tickling the cone” and it’s highly compressed but not collapsed sound waves. It resembles the regular roar of an airplane, but packed into a few seconds. Very different to a sonic boom, which sounds exactly like an explosion.
(The practical upshot is this strengthens your argument.)