Yeah sure there's a few countries where it's not the case, that's why I mentioned that but it's rare.
People can usually replace the app X with an app Y but there's a few apps which are categorically needed on a phone otherwise it hurts the phone itself. Banks & government apps are part of those and Youtube is one as well.
Those are the ones really preventing a third company to join in.
In fact in countries like Japan and South Korea nobody was using it until the last year or two.
This idea that any mobile device will fail unless it has X app is baseless. Everyone has a different set of X that is important.