It's a monopoly (or monopsony) if it's prohibitively difficult to function in the market if you refuse to do business with them (or, more commonly unless a regu

It's a monopoly (or monopsony) if it's prohibitively difficult to function in the market if you refuse to do business with them (or, more commonly unless a regulator is currently assessing monopoly status, they refuse to do business with you). For example, Google doesn't have a monopoly on search; I can use DuckDuckGo just fine (although patent trolling complicates this a bit). Google does, however, have a monopoly on search traffic; if Google delists your site, it has effectively disappeared from 90+% of peoples' (mis-)conception of the internet[1]. A government the purports to support a free market must[0] regulate the latter case. 0: in the sense that not doing so directly communicates that they do not in fact support a free market 1: and this could be true to a lesser degree even if it had only, say, 45% market share Edit: there might also be regulations that should apply to de-facto infrastructure like search engines regardless of monopoly status, but those are, by specification, not based on monopoly status.