But "the cost of extra shipping" has to be offset against the annual Prime fee, and all the perks you list apply just as much to vanilla (non-Prime) Amazon.

In recent years I've found myself swinging back towards buying things in brick-and-mortar shops, mostly because the delivery experience can be so horrible. Maybe things are better in the US, but in the UK getting things delivered is non-trivial when you work during the day, and even if you're at home, it's very common for UK postmen to not bother even bringing your parcel with them; they just leave a "while you were out" card forcing you to arrange redelivery. Delivery woes of various kinds have been a staple of /r/britishproblems since the start.