There is a tiny contingent that needs to be more aware, and that is the business owners and employees. There's just no reason to massively increase the cost when very simple things like washing your hands fixes the tiny chance of an issue. Don't lick your fingers when they have lead on them.
EDIT: Also the politics in this country disagree with your hypothesis. It would be so much harder to ban lead bullets than for people to wash their hands after they shoot.
Our capacity for free choice is implemented in our brains. Libertarians allowing this type of pollution seem pretty self-limiting.
>It would be so much harder to ban lead bullets than for people to wash their hands after they shoot.
Untrue, enforcing the washing of hands would be much harder than banning lead bullets. As there exists alternatives, most people would use them were lead bullets banned. Most people will not change their hand-washing habits. Banning bullets requires inspecting a few manufacturers. Enforcing washing of hands, basically impossible. Educating people to acquire more virtuous habits, ha - a blanket ban is a far easier to implement.
That would be incredibly regressive since the alternatives are all very expensive. It's also unnecessary because, as mentioned before, safe handling is far easier to achieve than a politically unpopular ban. You also don't really need to "enforce" safe handling beyond air scrubbing systems at indoor ranges.
There are also cases, such as blackpowder shooting and antique firearms, where non-lead projectiles may not be feasible. If I have an oddball caliber antique weapon I can still use it by casting my own lead bullets even if nobody makes commercial ammunition.