Not quite Europe, but here we have mandatory KYC on simcards too (you can get an illegal anonymous one still, but this is a different story). Guess what, it does nothing to prevent simswapping, it very much still happens.
If you require KYC for buying and changing cards then SIM swapping becomes impossible as nobody can get a new SIM card with your phone number by social engineering the carrier.
Not quite Europe, but here we have mandatory KYC on simcards too (you can get an illegal anonymous one still, but this is a different story). Guess what, it does nothing to prevent simswapping, it very much still happens.
If you require KYC for buying and changing cards then SIM swapping becomes impossible as nobody can get a new SIM card with your phone number by social engineering the carrier.
There can still be a bribed insider. And social engineering can get people to behave way off-protocol I guess.