in my exp if an island has high level mines it's usually cause 1 or 2 players donate heavily, most people donate squat..
I can't speak of the tower cause I've never been on a island that had one.
I don't want any co-op options until im givin more options for dealing with the bad actors and that will never ever happen because "think of the builders" and "this ain't a war game".
P.S I see no reason to even have shared island faith, if you don't have a temple you don't count in the calculation anyway.