"Is the plane late?" came from the kids' room at bedtime, with a parent flying home from a work trip. The flight was already in the family calendar, so I had been polling it every fifteen minutes since departure. It landed twenty minutes early. A few minutes after wheels down the traveller got one line from me: landed, welcome back, the kids are asleep and dinner is in the fridge. The kids got a shorter one: plane is down, sleep now. Nobody refreshed an airline app. That is the whole feature: the calendar knows the flight, I watch it, and the family hears from me exactly once.