If you're telling me the "greatest country in the world" can't transition to a sensible numbering system because it's "too hard" I will simply point you once again to the various other things Americans are hilariously and depressingly behind the rest of the world on... anything related to measurements, banking, healthcare, politics, comes to mind.
> why should it be relevant to me if you are connected to your choice of carrier by a piece of copper, fibre, radio waves or whatever else
because as someone else in the threaded highlighted, it can be abused (especially in the case of SMS which don't require you to 'pick up' to bill you) to a ridiculous level.
Something being missed is that callers are still charged to reach your phone company at the base rates - that is not free to them. You then pay your phone company extra for how you connect to them. Abuse is a red herring. When I go to other countries and get a local SIM I get inundated with SMS, which doesn't cost money but sure does cost a huge annoyance. SMS spam is very rare in the US, with the carriers cooperating to stamp it out and always refunding people for any.
The only sms "spam" I have seen.. I think ever, having had a mobile phone in Australia for ~13 years and now Thailand for about 2 years, is messages from the network operator (and its sister companies), here in Thailand. In Australia I don't remember ever getting "spam".
My point was not about "professional" spam, it was about the potential for personal abuse. Someone posted in the thread earlier about racking up $~200 of sms charges against a friend's ex girlfriend.
Try India sometime for SMS spam.
The US & Canada had far more companies, plus NANPA 3/7 format being hard coded everywhere - forms, computer programs etc. Trying to implement changes to phone number length will make y2k efforts look trivial.
Heck when places started requiring the dialling of area codes because "local" areas especially big cities had more than one, was disruptive enough. That started happening in the mid-nineties.
Given the choice between huge disruption, or termination fees being the same and the costs of connecting between the phone company and the person making/receiving the calls being their business, the latter isn't an unreasonable choice. When I call you, why should it be relevant to me if you are connected to your choice of carrier by a piece of copper, fibre, radio waves or whatever else?