Sure, some soils have lots of it naturally, but most don't. Lead's a natural substance, but you don't often find it naturally concentrated to the purity we use for industry/military/etc. Like most elements... say gold. Gold's all around us, with trace amounts everywhere, but finding nice big ingots of it is pretty rare (I know, I know -- someone's going to post a picture of one of those big nuggets -- it does happen, but it's rare).
It's amazing how much comes out of stuff you'd never expect... my firm had one project involving an old landfill that was putting a borderline toxic amount of lead and arsenic into the soil and water, purely from old (late 19th century and early 20th century) bottles, which often contain high amounts of both.
