Well in many countries you are required to show and submit ID to the provider that ties you to a particular sim/number. While I see this more as a control mecha

Well in many countries you are required to show and submit ID to the provider that ties you to a particular sim/number. While I see this more as a control mechanic than a security measure, it does give some reason as to why organisations tie identity to a phone number. I must assume that the USA does not do this?