It's also much rarer for someone to have multiple phones and the need to detect that connection.
So there are deeper tracking capabilities and it is easier to connect that tracking data with an official person in order to cross-reference.
Use a VPN and try to create all of the accounts you'd need to participate in society. It's impossible. You'll be lucky if you can get an email address. I can't imagine being un-banked or unable to afford a phone. You can't participate in modern (western) society without a (non-VOIP) phone number.
Also, there's no air gap on a phone. Devices will be correlated via location data, SSID scanning, etc.. Put two devices in the same house with wifi disabled and location data enabled and they'll be instantly linked as knowing each other.
1. They tend to trust a locked-down, reasonably secured environment more than a hackable, general-purpose operating system, especially for 2FA.
2. They’re under pressure from fintech, so they have to focus more on things customers want.