We had research to support the EPA phase down of lead.
Also, your assertion that lead “helps fuel companies” is fundamentally mistaken. Gasoline is a mass-produced commodity. Oil companies have single digit profit margins. These companies aren’t making Big Tech profit margins where they can absorb higher costs without passing them along to consumers. Cost savings from things like gasoline additives accrue to consumers at the gas pump.
Lead helped fuel company profits because it was cheaper than the other anti-knock additives, like ethanol.
tetra-ethyl lead helped significantly increase octane, allowing a lower-cost fuel to be used in gasoline engines.
Until the price of gas starts to remotely reflect the medium to long term costs of climate change I basically always celebrate anything that increases gas or carbon-based energy prices. Like, it sucks... but there's lots of data that consumers respond to these prices in their choices.
The way I think about it, the entirety of global civilization is massively, massively subsidizing carbon emission.