Unique attractions (e.g. cathedrals) seem to have plausible passenger success rates, but nonunique ones (parish churches, sports grounds, manor houses etc.) all persistently report 0% passenger success rate, even when conveniently connected to the transport network. Even for unconnected ones, I would expect some local success from walkers. I can upload a saved game illustrating this if really needed, but the problem is already visible in the start-up game.
Best wishes,
Matthew
This is because the success rate measures the proportion of generated passengers that reach their destinations. The game does not generate passengers from attractions, so no success rate will register.
I am in the process of overhauling the passenger generation system, including the success rates, for the next major release, which should make this position clearer.