I believe that 2002 means that they expect them to be replaced in 2002. Every car maker has consistently increased the rated lifespan of air bags as time has elapsed.

I have not heard of a single instance of an old air bag being tested and not working as expected, regardless of its age.

I guess it varies from car make to car make. On my 1991 Lexus LS400, it only states to have the airbag system serviced after 10 years, then every 2-3 years thereafter.

What service do they perform?