Yes, harsh on people literally choosing to spray a neurotoxic heavy metal compound over populated areas for their fun. Their advocacy is the roadblock to the adoption of safer fuels.

It doesn't actually accumulate in any particular area. There was a study done at at an airport that showed no particular accumulation at the airport. Leaded gas ends up poisoning the whole world a bit.

This "dilution is the solution to pollution" argument is the excuse the FAA uses for forcing everyone to use leaded avgas. This should be more of a scandal. The FAA is basically helping maintain a harmful oil company monopoly at the expense of the world.

This is not just about recreational aircraft. For example, 45% of the Canadian commercial fleet is piston engine based. Incidentally, Canada was involved in a test program with the FAA for leaded fuel replacements. The FAA recently dropped out of that program.

I think we'd all rather burn cheaper / more prevalent gas than a leaded fuel that is the output of specialty refining. We're not allowed to by regulation, though, and furthermore present solutions would also endanger safety in a big slice of aircraft. The fleet of general aviation aircraft is really old, after all.