Market share does not actually determine monopoly. You can have 100% market share and not be a monopoly. Conversely, you can have 50% market share and be a monopoly.
Apple has more active users in the US than Android btw.
The fallacy being repeated is actually people defining monopolies by referencing market share.
In determining whether a competitor possesses monopoly power in a relevant market, courts typically begin by looking at the firm's market share.(18) Although the courts "have not yet identified a precise level at which monopoly power will be inferred,"(19) they have demanded a dominant market share. Discussions of the requisite market share for monopoly power commonly begin with Judge Hand's statement in United States v. Aluminum Co. of America that a market share of ninety percent "is enough to constitute a monopoly; it is doubtful whether sixty or sixty-four percent would be enough; and certainly thirty-three per cent is not."(20) The Supreme Court quickly endorsed Judge Hand's approach in American Tobacco Co. v. United States.(21)
Following Alcoa and American Tobacco, courts typically have required a dominant market share before inferring the existence of monopoly power. The Fifth Circuit observed that "monopolization is rarely found when the defendant's share of the relevant market is below 70%."(22) Similarly, the Tenth Circuit noted that to establish "monopoly power, lower courts generally require a minimum market share of between 70% and 80%."(23) Likewise, the Third Circuit stated that "a share significantly larger than 55% has been required to establish prima facie market power"(24) and held that a market share between seventy-five percent and eighty percent of sales is "more than adequate to establish a prima facie case of power."(25)
It is also important to consider the share levels that have been held insufficient to allow courts to conclude that a defendant possesses monopoly power. The Eleventh Circuit held that a "market share at or less than 50% is inadequate as a matter of law to constitute monopoly power."(26) The Seventh Circuit observed that "[f]ifty percent is below any accepted benchmark for inferring monopoly power from market share."(27) A treatise agrees, contending that "it would be rare indeed to find that a firm with half of a market could individually control price over any significant period."(28)
Some courts have stated that it is possible for a defendant to possess monopoly power with a market share of less than fifty percent.(29) These courts provide for the possibility of establishing monopoly power through non-market-share evidence, such as direct evidence of an ability profitably to raise price or exclude competitors. The Department is not aware, however, of any court that has found that a defendant possessed monopoly power when its market share was less than fifty percent.(30) Thus, as a practical matter, a market share of greater than fifty percent has been necessary for courts to find the existence of monopoly power.(31)
Unless you believe a market that includes nearly the entire population of the United States to be "typical", are we not then in agreement that Apple can still be found to be a monopoly, according to the excerpt you just posted?
The relevant geographic market for this court case will be the entire United States, yes. It is possible, but rather unlikely given existing historical precedent, that Apple's current US market share will be considered a monopoly.
Apple has more active users in the US than Android btw.
The fallacy being repeated is actually people defining monopolies by referencing market share.