What would you do instead?
You are also forgetting it is easy to mask, obscure, and hijack numbers. So it doesn't cost money per number, many times they can use their own number.
There isn't a universal solution, which is the main problem here. Sometimes numbers make sense, most of the time not.
But you’re OpenAI. You need to do _something_. What do you do?
Stop doing things just because others do it. You'll never find a better way if you're always following. You'll never find better ways if you just accept things as they are. If you never push back. Let's be real, the number isn't about identity verification. They have my name and credit card. Unless by "verification" you mean cross matching me with other databases with the intent to sell that information.
You keep pestering me but you won't ask why they need that data. Like you just accept things at face value?
Seriously. How can the most prolific means of spam be used to prevent fraud and abuse? (Okay, maybe email is a little more prolific?) Like have you never received a spam call or text? Obviously fraudsters and abusers know how to exploit those systems... it can't be more obvious...