After dropping off the last kid, the bus driver rides back to the lot alone. Wave from the curb anyway.

Shifts have an ending nobody is present for. When the last stop is done, the route is still thirty minutes of empty seats back to the lot, then paperwork and a walk to a car. A wave is the one thing you can send into the rest of it.

Wave from the curb after you get off, even though the bus is already moving and nobody is required to notice. Do it on the ordinary days, not just the last day of school. Small acknowledgements are most useful to the people whose work ends in an empty room.