Why are some company's auto customer services so easy to use, and other's are so hard?

Company A has an auto teller who picks up, asks for your account number, your SS number, your birth date, and how many dogs you have. Then it sends you to another auto teller who asks the same questions. Yet again, another auto teller who asks the same questions. Then it hangs up on you. Or, maybe, you’ll get to talk to a human who asks the SAME questions again then says they can’t help you.

Company B says, “If you want to pay your bill press 1.” And then it easily, and seamlessly walks you through paying the bill. Piece of cake.

Why such huge differences in companies? And do they ever review their systems, posing as a customer, so they can see how frustrating it gets?