And....it worked pretty much exactly as designed - initially only the largest stations carried it because they could justify the storage costs, and eventually it disappeared from almost everywhere. Just before covid there were still 3 small garages selling leaded petrol by the drum, but afaik they all stopped doing so.
And regardless - you can stil buy actual real Tetraethyl Lead fuel additive which turns your petrol into actual real 4-star leaded petrol, just like in the old days:
https://www.demon-tweeks.com/tetraboost-e-guard-15-fuel-addi...
Aviation gasoline is probably the one market that still keeps it afloat, when/if piston aviation switches over the remaining market is small and insignificant.