Sloppy technique and careless behavior have nothing to do with wheel weights, pure lead, or other heavy metals. Wheel weights aren't the culprit (no more dangerous than pure lead or pure antimony or pure silver or pure mercury or pure chromium or...) - poor ventilation, failure to wear gloves, lack of clean up etc. is the issue.

Breathing fumes or ingesting particles of heavy metals is bad news - doesn't make a difference which metal it is really, all of them will kill you. Up to you to be careful.

Are you arguing for more government regulation? If the government made sure wheel weights were 100% lead they would still be deadly if you were sloppy or careless.