Imo it's because the PPV is retarded and only the USA still insist on using it.
I have a sport channel for which I pay €27/month for, this broadcast the national soccer games, international, premier league, etc, and also other sports. That amount is already quite expensive for a sport channel, but it has everything I need to see. But no way in hell I would pay each onth around €50 just to see 1 event. I would however pay around €30/month for a complete channel that broadcasts the events.
I think BT sports in the UK broadcasts all PPV's?
And it also gives a wrong perception about the amount of people watches the events. Less and less people are willing to pay 60 bucks for a PPV, so they stream, go to a bar, download afterward etc... But more and more people start to watch UFC (at least in my country) in countries that don't have PPV. They have a channel that broadcast it or resort to other means. In Belgium there's no legal way to watch a PPV.
I think it was for UFC 205 you could stream the PPV on youtube live for €20.
I don't know how much fight pass is? But they should sell 2 versions, 1 regular one, and 1 a bit more expensive that broadcast PPV events live.