If we all stopped using AWS and started using something else, eventually it would become the same thing.

Eh. The cornerstone of most of these big firms is some amount of government or government-adjacent contracting.

That's what makes them convenient. They adopt uniform integrations. They operate in bulk. They have enormous staff. You're nibbling around the edges of a much bigger and more complex system.

The solution to Amazon isn't to patron some Mom-And-Pop retail frontend (that almost certainly also uses Amazon for shipping). It's to nationalize Amazon and incorporate it into the USPS.