Earlier quoted context omitted.
That’s down to your network. I was able to buy an e-sim over the internet in a few minutes from Vodafone UK, while not even being in the UK, and set it up by scanning a QR code that got emailed to me. Your problem isn’t the e-sim, it’s a shitty network.
> buy an e-sim 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.