Yeah, I was surprised to see it too. I had heard about the 73' Impalas having the airbags (only 1000 of them), but had never personally saw one before, except one in an old "Allstate" insurance ad in an old Time magazine that I had. Out of only 1000 with the option, I would say this is probably one of the last remaining with the option. Oddly, in different Allstate ads from the early 70s, some showed the airbags in early 1970s Mercury Montereys and Marquis', but not sure how many of those were equipped.

Many more (but still rare) of 74-76 Oldsmobile, Buick and Cadillac with the airbag option still remain, since 10,000 were equipped with the option, but even 10,000 is a low number for a car made so many years ago. You do not see many with the option these days.
As mentioned, my grandmother had a 74' Oldsmobile Toronado with the dual airbag option and I came very close to purchasing a 20K actual mile, 74' Buick Electra 225 4dr with the option as well about 2 years ago. An interesting side note- the tilt wheel option was not available on the airbag equipped models. Obviously, the technology was not up to par back then to have both together.