When Amazon asks if my email address is all lower case... The desire to make it an informative moment that email addresses are not case sensitive is outweighed by my desire to resolve my issue as fast as possible.

Technically you're wrong. RFC821/2821 explicitly defines anything but the local part of the address as case insensitive. The local part can be case sensitive.

There are no systems today that really handle it case sensitive, that would only cause trouble. But if you wanted, you could.