Ok, this is what we found out practically.Did you request for new i94 for your wife while coming like you had mentioned?
No new I-94 for AVR in most cases as I had a good chat with the officer. They are issuing I-94 if for some reason something is flagged in their system and they ask you to park your car and walk into the building to check any additional info. Issuing new I-94 is a little time consuming and they can't do it at the drive through.
Ok, coming back to our case, we crossed the border using AVR a few times with no new I-94 and standard questions. In the most recent trip, my wife got her visa stamped in Toronto and because we are entering the U.S. after a visa has been stamped, we had to walk into the office to verify a few things and they gave a paper I-94 at that point stapled to the passport. They confirmed it is only because it's the first time she was entering after getting the visa stamped and any subsequent visits should be quick without getting out of the car.
Hope this helps.