My understanding is that if a lead acid battery ends life in the landfill, somebody has seriously messed up. In the US at least, the vast majority of lead from batteries is recycled, usually into fresh batteries, thanks to financial incentives and a very efficient collection system primarily run by auto parts stores. It's unclear to me whether it's actually more efficient to reuse an old lead acid battery, or to recycle its lead into a modern battery with higher capacity, it probably depends on the specific circumstances.