Almost all the cooks/childcare providers, office support, etc are contractors not employees. A significant amount of SWE and other technical roles are contractors as well.
The mechanism by which they get paid (W2 vs 1099) isn't important. The parent comment was listing several occupations that people fill at Google that don't fit the idea of "highly compensated software engineer" as examples of people who may be interested in organizing in search of better working conditions.
For what it's worth, I don't agree with the implication of the comment--it isn't fair to say software engineers can't have any reason to organize or protest against things that their company does.
For what it's worth, I don't agree with the implication of the comment--it isn't fair to say software engineers can't have any reason to organize or protest against things that their company does.