It is a fair point, and you can, in fact, buy lithium-ion 12V batteries. The economics, safety, and performance characteristics are the answer. But, those lead

It is a fair point, and you can, in fact, buy lithium-ion 12V batteries. The economics, safety, and performance characteristics are the answer. But, those lead batteries are sealed and recycled, and don't usually contribute to environmental or human health issues. Although, it would be better to move away from them. Newer solid state batteries would possibly fit the bill, but not soon. By contrast, lead water pipes, lead paint, and leaded aviation fuel all do directly spew into the environment and into human bodies.