I remember some car rental system switched from having you enter your confirmation number on the keypad to voice recognition.

I'm most likely to use this system in a busy airport. After enough times of it not understanding me, it finally put me on hold for half an hour for me to read the number to a person. Something that took me less than a minute previously now was super frustrating.

I must not have been the only person this affected because they added back in the option to use touch tone.