The fact that an undefeated team can be not be champion has way more to do with the structure of the sport than the number of games. Specifically:
A) The number of teams. FBS has 131 teams, which is about four times as many as any of the leagues you mentioned. As far as I'm aware, it would also be 4x bigger than any other sports league in the world.
B) It's made up of independent conferences with different priorities, resouces, operations, even referees. Again, no other sport you mentioned has anything like that. Yes other leagues have conferences and divisions, but they are still part of the same overall organization, share revenue, make decisions together, etc. Nowhere else do you have conference championship games where only part of the schedule counts but then the sport's championship game counts all of the games but also that has to be determined a lot by eyetest because there are very few out of conference games so going just by record wouldn't make sense.
The main way to "fix" how college football determines its champions is not just to slap more games on the season, it's to change the structure to be more simliar to the leagues you mentioned, although of course that comes with its own downsides. But if you keep the structure the way it is and just increase the number of games by 50%, you could easily still end up with an undefeated team that isn't champion.