If one is late enough that one uses an app to tell others that one is late, then yes. If one needs to be somewhere half an hour away, one does not leave 30 min

If one is late enough that one uses an app to tell others that one is late, then yes. If one needs to be somewhere half an hour away, one does not leave 30 minutes beforehand; one leaves 35-45 minutes beforehand, or even more, depending on importance (e.g. one probably leaves for one's wedding very early indeed, just in case a bridge drops and one's engine drops on the same trip). Arriving late says, 'I either did not care enough about you to leave early enough, or I did not care enough about you to accurately model the journey duration to anticipate delays.'