Is eSIM Quick Transfer not fully supported ?

Apple support documents on eSIM mention that Quick Transfer of an eSIM from one iPhone to another is possible IF your carrier supports it.

Why is this so? A physical SIM moved between two iPhones do not require any intervention of the carrier, then why would an eSIM ?

What if a carrier supports eSIM but doesn’t support Quick Transfer? How can one possibly transfer an eSIM for a scenario?

And finally, is there any official or unofficial list of carriers that support Quick Transfer?