It took that many years to collect enough research and attention on the topic, and then force the industry's hand by regulatory measures, and it only worked because when the lead phaseout started, there already were alternatives developed. Without all that, the market wouldn't self-correct at all.

I mean, it's such a common failure mode of free markets, it should IMO be taught to kids in schools. If a product/service has damaging side effects that aren't immediately apparent, or the damage is diffuse, or takes a long time to manifest, then the market is blind to those costs. A product that mitigates these side effects is usually more expensive. Such a safer alternative isn't competitive on the market and won't succeed until it becomes as cheap as the less safe one (or cheaper than it).

Conclusion being: don't expect the market to correct against profits on its own. In fact, it will resist correction, so for the change to happen, you need strong regulatory pressure and/or innovation aimed at making the correction more profitable. In reality, you need both.

Not quite, it was known to be a bad idea at the time, and there were alternatives available. So...why? Because market control, patents, and the usual cast of idiots having nothing to do with "doing the right thing":

https://www.smithsonianmag.com/smart-news/leaded-gas-poison-...

> Lead's toxicity was recognized and recorded as early as 2000 BC