It is an open secret that criminal groups also pay unscrupulous T-Mobile employees to assist with SIM-swap attacks. I am not sure at what scale this happens, as those instances _should_ be easy to trace and prosecute. But I have seen evidence of criminals reaching out and offering "side work" on the T-mobile subreddits, as an example.
In those cases, hardware keys for employees would not help.
In those cases, hardware keys for employees would not help.