Which can, and should change to something better than providing the SSN and passcode of the mobile network primary account holder who “owns” that phone number.

If anything, your experience should lead you to advocate to a quicker change to eSIM, so that your dad can control his phone number without needing someone else’s SSN.

Given that so many things are tied to a phone number (they shouldn't, but are), there should be strong authentication measures to transfer phone numbers.

Your problem isn’t the e-sim, it’s a shitty network.

So no, I'm not going to applaud giving the networks even more power over my ability to switch phones and SIMs. Physical SIMs are nice because I can 99% cut the network out of my decision to switch phones -- all I have to do is pop the SIM into my new phone. I do not want to go through Verizon's, AT&T's, or any other archaic provider's process when dealing with my (or a family member's) phone upgrade.

It's a lot like the headphone jack removal: replace something that works great with a solution that works OK 90% of the time. But 10% of the time you're stuck in an edge case that isn't covered at all by the new, shinier solution.

I wasn't trying to buy a new number, I was trying to transfer an existing one. It doesn't surprise me that they make it as easy as possible to get a new one.

Not that that's unusual, most of the networks are crappy - vodafone was the only UK network I could find that didn't require you to go to one of their stores to get the QR code. Artificial barriers are erected at every turn.