Earlier quoted context omitted.
The Apple thing doesn't work though, for a specific reason: it's a very common word/name. Smith is a very common surname. If one person starts the Smith Automobile Company and another person starts the Smith Farm, obviously there's no issue there. That's because none of us invented "Smith", it's understood to be a common name, etc. On the other hand, if I start "The Google Paper Company", I'm pretty damn sure I would…
That is not how trademarks work. Feel free to start the Google Paper Co. Uniqueness is not a merit for trademark infringement. To infringe you have to be a competitor.
Mcdonald's was able to show that there would be consumer confusion DESPITE Mcdonald's not doing hotels nor Mcsleep inns not doing food.
As a result, Mcdonalds basically has an open trademark enforcement on "Mc-" whatever.
While I'm not fond of the judgement here, it was nonetheless decided thusly, and contradicts your otherwise accurate (so far as I know) statement. (And to weaken my own point, I believe Apple lost a similar case about i, so nothing here is clear and reliable.)