But, my company does employ thousands of software people. We just don't sell consulting, sell software to other people, or sell products that use software.
You misunderstand. The third group is not only companies that sell software-based products, the third group includes companies that use software to sell their products or manage other aspects of the business. Having an in-house online store is an example.
That presumably puts your company in that group, just like mine (or else I have no clue what thousands of software people would be doing on the payroll).
I bet our two companies have very different reliances on technology, but we're both in the same group, because all of our software supports our sales of our actual goods and services.