The problem with lead is not that it's poisonous, but that it affects the brain. Especially in children. No amount lead is good and the other uses should be banned as well but due to rich people (those who can afford to fly private planes) it's still allowed.
That might be true, but has basically no bearing on the ban vs tax debate at all.
I don't think anyone made an argument one way or another _how_ lead is bad: all the arguments so far works just as well whether lead is 'poisonous' or bad for the brain in some special way.
You are right that private planes are mostly used by rich people. But that's not true of all products that contain lead, or processes that emit lead into the environment. (For example, there's lead in some batteries and there's lead in some solders. See https://en.wikipedia.org/wiki/Lead#Applications for more.)
The harm of lead is finite, and thus a finite tax would be a reasonable way to deal with it.
In practice, we already tax/fine companies for killing people.
So I'll bite the bullet, and say: yes, of course. Ideally, a large part of that tax would go towards (the estate of) the victims. That's more productive than locking people up: that's just a straight up loss for society.
We also already tax stochastically-killing people; or in some cases, we don't even tax it and just allow dangerous activities. Eg we allow people to drive cars and we allow people to run coal-fired power plants.
Going from a small percentage chance to a larger percentage chance (nothing is certain) is not a qualitative difference, only a quantitative one.
The really rich people all have jet planes which burn jet fuel (no lead.) It's the upper middle class that have lead burning piston prop planes. Dentists and doctors, not billionaires.
Anyway, unleaded fuel is now approved for those planes so the transition should be pretty quick now.
Yes, it's somewhat funny. Our commenter consp almost suggested that people with private planes _want_ to burn leaded fuel, when unleaded fuel wasn't even legal to burn in them.
