Amazon hires warehouse employees directly, though, so in a sense they are employees of a Big Tech company even if they’re not doing tech work.
The situation in this article would be more like the contracted electricians who work on Amazon warehouse buildings complaining about their electrician employer company and then the journalist trying to pin those complaints on Amazon because that’s where the work was done.
The “contractors” in question here have a supervisor at Google, and the pay they receive is from Google via Modis. If Modis didn’t exist to be the contracting party the employees would be indistinguishable from full time employees under Google’s employ. Arguing that the contracting relationship is all that is needed to justify this is like arguing that I can form an LLC to hold my assets and receive my salary to avoid personal income tax.