If you've ever used AvGas, you'll know why people use it. (As long as you have a good highish compression engine.) Once upon a time, back in the first Gulf War, I was able to purchase AvGas 3c a litre cheaper at Ballarat airfield than Super anywhere in town . I have a picture somewhere of the Dwarf lined up for fuel behind a Cessna. The smell is wonderful, too. Ahhhh, nostalgia!
FWIW, you can use JetA1 (Gas Turbine fuel) in diesels. You can run it straight, but I'd run a 50/50 shandy personally.