I call out basically so that the pass-ee isn't startled when I'm suddenly next to her. It's my responsibility to pick a safe line, even if I have to go into the traffic lane.

Sometimes people don't ride as far right as possible because they're afraid of road trash, being pinned against the curb, etc. I respect that. It's nice if they move but not required.

Joggers, walkers, or bicyclists who look inexperienced, I yell out "GOOD MORNING" when I'm still behind them so they know I'm there. Then, I wait a few seconds to see how they react before I pass. Most of the time, people thank me for announcing my intentions. (Of course, all bets are off for people wearing headphones...)