Explanation: The Romans used lead-lined cookware not in ignorance of its dangers, but wholly cognizant of them - the Romans recognized lead poisoning from various sources, and regarded lead as 'unwholesome' to human health.
They used lead widely in many applications that they could be forgiven for thinking were not dangerous - they understood how to prevent lead leaching in pipes, and used lead in writing tablets. Less forgivably, in cosmetics. But most dangerous of all was the use of lead pots in making 'defrutum' - sweet wine jelly syrup, which wealthy Romans loved to put on everything. The thing is, the process uses lead specifically because other materials won't do - copper and iron leave an aftertaste, while lead vessels actually make it sweeter, as lead itself acetate is slightly sweet.
What's a little harmless poison in your condiments, after all?
We also put lead in gasoline knowing damn well it would come out the tail pipes and people on the streets would have to breathe it. Several decades of leaded gasoline passed until someone developed an alternative to fix engine knocks. If that had never been invented we would still be pumping lead into our streets today as a "cost of life" or more realistically, a cost of doing business.
We use Teflon-coated cookingwear even though we know it's poison.
Yes, yes, I know, technically it's not a problem if you don't scratch or over-heat it. But in my experience, 99% of non-stick pans get scratched and over-heated.
You say this like we don't still have kitchenware with lead (or other nasties like cadmium) in them, often for purely aesthetic reasons. Most of these are discontinued products still in circulation, but some are still being produced (in theory they're "safe for use" because the heavy metals are sealed behind something nontoxic, but scratches and chips may expose them).