No one cares as long as you are using HTTPS, which is the point.
If you aren't using HTTPS for all of your site, you are vulnerable to MITM attacks.
If you aren't using HTTPS for all of your site, you are vulnerable to MITM attacks.
Or did I miss the point of your comment?
Given that, another attack might be to mitm DNS and serve an entirely fake Amazon site, all in HTTP, and the user will not notice there's anything wrong.
I think that's the point mro and troels were trying to make.
The only way I can imagine to mitigate this would be to use HSTS on the amazon.com home page.