I imagine that premier events will always be held at public-accessible places. I'd say official leagues should also be held at public locations. The prizes for both these activities are PUI-supplied.
Regarding sanctioned tournaments, I'll restate my opinion. They should be open to the public and timely. But, there my be circumstances where POP might waive that requirement.
ukpokemonpro, here in the US, most military bases require a military ID or base pass. Walk-in passes are usually available to the general public, but during military exercises and threatcon elevations, walk-in passes are sometimes withheld. But, many bases separate the personnel housing community area from the military operations area. These housing areas usually have schools and youth centers, and are less or non-restricted. I'd see no problem in holding sanctioned tournaments at those nearly-public-accessible locations.