We still do for piston aircraft, thanks to intense lobbying by the aviation piston engine industry.
There's even a 100LL alternative that has sailed through most tests the FAA requires but the FAA has been stonewalling them for something like a decade. The FAA is full of paper-pushing corrupt beaurocrats who are firmly in the pocket of industry, as demonstrated by the thousands of victims of Boeing crashes from the idiocy of the MAX program (wherein Boeing did not want to spend the money to redesign an aircraft for bigger passenger and cargo loads, so they just stretched the plane, which put the Cg out of whack, which meant they needed to have a computer help fly the plane...and then skimped on redundancy.)
I don’t think that an unleaded fuel is 100% ready to go, but you’re absolutely right that the FAA is a huge reason why. My plane is certified for 80/87 (a fuel no longer produced) but the paperwork involved means I’ll just keep burning 100LL for the foreseeable future. With all the engine damage that incurs.
I'm sure you wouldn't throw stones from a glass house. Either way, I suspect you're reading what I wrote as "well, this is easier and I don't care enough to put in the effort." Conversely, there is currently no realistic (not to mention safe) path forward. I am subject to significant and rigid regulation that precludes any other action. My comment was intended to point out the absurdity of the situation in the hope that awareness can lead to change.
Aviation is currently going through a chicken & egg situation much like the electric vehicle charging network. Unfortunately, it's hampered by regulatory inertia. To blame that on an individual is wildly counterproductive.
It seems more like an incredible feat of bureaucratic perverse incentives. How is the thing that poisons people the default and the thing that doesn't is what requires specific government-imposed costs?
Didn't Toyota (note I'm not an expert) build a diesel that they hoped to certify for smaller planes since it can run on standard jet fuel but couldn't get it approved and abandoned it?
There's even a 100LL alternative that has sailed through most tests the FAA requires but the FAA has been stonewalling them for something like a decade. The FAA is full of paper-pushing corrupt beaurocrats who are firmly in the pocket of industry, as demonstrated by the thousands of victims of Boeing crashes from the idiocy of the MAX program (wherein Boeing did not want to spend the money to redesign an aircraft for bigger passenger and cargo loads, so they just stretched the plane, which put the Cg out of whack, which meant they needed to have a computer help fly the plane...and then skimped on redundancy.)