I wonder if the result could be less about the lead itself having a direct effect on behaviour, and the action of the removal of lead being identified as "somet

I wonder if the result could be less about the lead itself having a direct effect on behaviour, and the action of the removal of lead being identified as "something obvious and beneficial which would be good to do" as being coincident with a greater enlightenment amongst those making the rules? I.e. to what extent "we should remove lead from petrol as that is obviously bad" is actually a handy indicator of more considered minds running the shop, those minds also being more predisposed to the kind of other "obviously good" decisions which could also have brought about an eventual reduction in crime.