Get yourself a job with an Ag operator that works rice. Chances are he will not turn you loose untill you can do what these folks do.
Its a safety thing.
As for bad examples...Red Arrows, Blue Angels...all those nasty aerobatics at low level...downright dangerous
Currawong, you have been counting sheep too long. Ag operators do things like this not as a "Safety Thing" but as a "Lets see how good you really think you are, thing". Ag folks have a horrible safety record.
As to the demo teams being dangerous, sure, more than the average flyer. It goes with the territory and if you cant handle it you shouldnt be there. Danger for the most part is restricted to the participants. Albeit some get to close to the crowds as we have seen in the past.