There is a common misapprehension that the term "monopoly" can only be used when there a single supplier.
Quoting https://en.wikipedia.org/wiki/Monopoly : "In law, a monopoly is a business entity that has significant market power, that is, the power to charge overly high prices, which is associated with unfair price raises."
Or from Milton Freedman, "Monopoly exists when a specific individual or enterprise has sufficient control over a particular product or service to determine significantly the terms on which other individuals shall have access to it". https://archive.org/details/capitalismfreedo0000frie/page/12...
In the post-Borkian interpretation of monopoly, adored by the rich and powerful because it enables market concentration which would otherwise be forbidden, consumer price is the main measure of control, hence free services can never be a monopoly.
Scholars have long pointed out Bork's view results from a flawed analysis of the intent of the Sherman Antitrust act. For example, Sherman wrote "If we would not submit to an emperor, we should not submit to an autocrat of trade, with power to prevent competition and to fix the price of any commodity.” (Emphasis mine. Widely quoted, original transcript at p2457 of https://www.congress.gov/bound-congressional-record/1890/03/... ). Freedman makes a similar point (see above) that a negative effect of a monopoly is to reduce access to alternatives.
One well-known rejection of the Borkian view is in Lina Khan "Amazon's Antitrust Paradox" paper. https://yalelawjournal.org/pdf/e.710.Khan.805_zuvfyyeh.pdf
In it she quotes Robert Pitofsky in "The Political Content of Antitrust":
"A third and overriding political concern is that if the free-market sector of the economy is allowed to develop under antitrust rules that are blind to all but economic concerns, the likely result will be an economy so dominated by a few corporate giants that it will be impossible for the state not to play a more intrusive role in economic affairs"
(I can't find a copy of that source online, but you can see the quote at https://archive.org/details/traderegulationc0005pito/mode/2u... where Pitofsky rejects viewing antitrust law through an exclusively economic lens.)
Even if you support the Borkian interpretation, you should still worry about the temptation for the US government to "play a more intrusive role" with GMail accounts. I strongly doubt Google will follow Lavabit's lead and shut down email should the feds come by with a gag order to turn over the company's private keys.
In the name of national security, of course.
