There is this thing called the telephone, or text. I have had people call me with verification codes or text them to me on rare occasion.
The fact is that where there is a will there is a way, and particularly when you, and the client, are "in cahoots" with each other.
MFA keeps "the random stranger" from having unauthorized access. It certainly doesn't, of necessity, prevent a tech legitimately working in consort with the actual account owner from having authorized access. It just requires coordination.