They are talking about technical people, not blue collar jobs.
These articles always get it wrong by completely failing to distinguish who exactly the TVCs are. They'll interview a less common white collar contractor but then use numbers for total contractors. A decisive majority of the actual white collar workers are FTEs.
The only contractors I work with, and not too closely at that, are the tier one support people for our product in the Philippines. And then there's some web developers, designers, and project managers who work for a web design firm, but their job seems pretty cushy so I wouldn't include them in this conversation.
Every company uses agencies for all sorts of things: recruiting, marketing etc..
But when you bring people in house, if they're working 'in' your company ... then almost universally they are 'employees'.
These are not 'security guards' or 'cleaners' who exist almost outside the scope of the work, they're very much within it.
If you're in HR at a bank on Wall Street, doing 'recruiting' - odds are you work for the company, not a contractor.
It's very rare to see a large tech firm contract directly with an individual employee, and it would be incredibly rare to see it happen with a lower paid position. I've never seen it personally.
Quite a few of the people I've interacted with were contractors. You can sometimes tell from their email signature even if the email address is @bank.com.
The NYT article is talking about 121000 contractors.
Either Google has 121000 white-collar contractors, or the article also talks about blue-collar jobs.