My point is that liability for consequences determines who (and if) does due diligence. If there are no remedies then customers are on their own, and either they do due diligence themselves or there is no due diligence at all; but as soon as the seller has to bear financial consequences for selling noncompliant product, suddenly they will become very capable of effective due diligence.

It's all about the incentives and motivation; companies which are permitted to offload risks to consumers will do so and ignore even trivial measures they can take to reduce these risks.