This assumes the provider wants to be nice and make it that way - yours does in this case. eSIM however gives them the option to make the QR codes single-use and require payment or additional verification before giving out another one.

Some commenters here are correctly saying that the carrier could technically prevent physical SIMs from being moved between phones by restricting which IMEIs are connecting to the network, but that's not usually done and there's an established convention that SIM cards can be moved around. eSIM gives them a blank slate to start over and break that convention without much backlash.