How can Amazon mislead in their listings legally?

Other way around. Amazon lobbied hard *in favor of *the imposition of sales taxes. Now that it’s a big company, the resources involved in complying with the dozens of sales-tax regimes in the US are relatively bearable, and this provides Amazon with a competitive advantage against smaller retailers who cannot comply nationwide with the same ease.

I’m in the UK and even if I only buy a single item from Amazon UK, there are no shipping costs if I’m prepared to wait 3-5 days for delivery.
This option is called ‘Super Saver Delivery’.

I think it’s like “Compare to Similar Electric Waffle Irons” on this page.

Honestly, I’ll have to do more reading to figure this out, but it’s not as simple as Amazon being a big fan of taxation, and wanting to tax from the beginning. They know they can’t beat the government, but that doesn’t mean that they are going to tax if they don’t have to. E.g. [1] and [2].

The US has that too, which is what people are talking about above. It was $25 for years now $35. However, it looks like that’s not true in the UK, but you could be forgiven as it looks like the change is very recent: as of today, there is a £10 threshold for Super Saver. WAG: I’ll guess that the discrepancy ($16.40 vs. $35 or £10 vs. £21.34) is because the UK is much smaller.

I see the same “FREE SHIPPING on orders over $35” text.

Edit: Oh, I see what you mean, in the table below. There’s no asterisk or the “on orders over $35” text.

That’s exactly it, yes. I’m no good w/ screenshots uploaded to hosting sites on any of my ancient computers now, my apologies. That whole table row that says Free Shipping is almost certainly inaccurate, I realize now. But even the asterisk would make it more accurate, as we consumers know an asterisk means ‘not really’.