Amazon is clearly not a lemon market (and by clearly I mean it's a textbook case). Amazon is a company that guarantees/warrants the products (buyers have effective recourse to return products). In the paper's model this prevents a lemon market.

Still, I feel more and more annoyed using it because I can't trust the quality. A warranty is still annoying when dealing with low cost items

I think that the presence of effectively meaningless warranties is ripe for exposure.

Unlimited replacements for a $40 screen protector? Just send us $20 to ship you the free replacement.

Business relies on government for enforcement of contract and commercial law, but simultaneously creates intentionally confusing terms and fights against the authority of government to enforce the other side (for the consumer).

In addition to the information asymmetry, there's an overall power asymmetry -- both need to be addressed.

In the US, yes. Otherwise the goods will be shipped from other countries and it will often be impossible to return them or get refunds. Amazon does as little as it can get away with there.

This is not by accident, since most people then choose the shipped&sold by amazon itself, of course potentially more expensive.