[shantly]

Corporations have far more resources than individuals, and a much smaller set of things to worry about, if this is limited to inputs or products the company themselves are responsible for creating or having created (not, say, office chairs and pens). Individuals can't just "put a person on it" (they are the person—perhaps there are a few in a household, but they still can't afford to make it any one person's job) and they consume a much wider variety of things from many more sources than your average business does (again, constrained to things core to its business).

"Well why can't they restrict themselves to a smaller set of products the supply chains of which they can verify?" well yes, they could, but this is plainly still vastly more burdensome than asking a company to simply make sure the much-smaller set of folks involved in its supply chain aren't killing kids, given the vast resource disparities between the two.

So, while pushing liability "to the end of the chain" may satisfactory complete some kind of line of ethical reasoning, practically speaking it's just a way of saying "I'd rather we do nothing". Pushing the liability to companies might actually accomplish something, without undue burden (as pushing the liability to consumers would, I think it's clear, surely have).

At any rate, isn't the market supposed to be great at sorting these things out? If we could let market-based solutions take over the role of things like food safety certification without massive increases in risk and decreases in convenience and wild inefficiency, as I've seen proposed, then surely these companies can figure out some way to organize a market for supplier validation and inspection that solve the problem more efficiently than government directly inspecting and certifying every part of every supply chain. Right?