Was just thinking something similar: why aren't calendar apps smart enough to book commutes for themselves? Like, if one books an appointment at one's dentist on a day one has already booked oneself at work, and if one has locations attached to those appointments, why can't the calendar pop up a dialog, "Calculate commute time?" and if you authorize it too, it talks to google maps or whatever, and then books the appropriate amount of travel time onto the calendar as an appointment, and sets one's default notification for such things on it, so one gets pinged "Leave for dentist in the next 15 minutes" or whatever.

It could even, at T = commute duration * -2 from the appointment, go check realtime data about traffic conditions, and adjust accordingly, with notification, e.g., "Traffic on I93 north of here sucks, commute adjusted 10 minutes earlier".