There are entire countries where one company has 93%+ marketshare. Yes, maybe people can go to another country where the marketshare is different, but do we all seriously think that the global marketshare not resembling a monopoly definitely means that there's no one market where a monopoly exists?

I imagine trying to effectively use (or market) a competing product in a region with 93%+ marketshare is a painful experience, regardless of whether the global marketshare is more balanced.

Using global marketshare hides details like that. Apple could have 100% of the market in China and India, and Android could have 100% of the marketshare in the rest of the world. This would put, worldwide, Apple at about 35% and Android at about 65%. I would argue there are clearly monopolies in that case, though, even if the worldwide numbers are 65 and 35.