In an ideal world you could trust the cell phone operators to diligently protect your number and you could rely on this to help Google/Chase/GoDaddy identify your account. The problem is this makes it complicated for the cell phone operators and why should they be the ones to have to enforce your identity protection to benefit FANGs/Banks/etc? It always seemed a bit dumb to me that you need a phone number for most accounts in this internet age.
Maybe they could offer a service for a fee where they will be stricter and you have to show a passport to the office to get a new sim issue.
In the meantime I'm sure they've figured out its more benefical in the long term that they just sell cell phone plans that are flexible and we need a better solution to identify people and their accounts.