How can I change all links in the store to be https if the site accessed via https?

[one tall man]

Oye, that's an entirely different action/request. What is expected to occur at say the login page, or checkout? And then again after such page(s)?

The answer to can it be done? Absolutely it could. What is the "advantage"? What is the benefit that you are seeking to gain? Or what problem is trying to be prevented?

I'm wondering, though can't say that I've tried it if you changed your HTTP_SERVER to just //mydomain (dropping the http: and/or https:) how it would respond/react. The whole thing is deeper involved than just those one or two constants, but it makes me wonder.

If a site user enters the site via https, they expect that their entire session will be SSL encrypted.
If a site then redirects them back to http, their expectation is violated.