Driving the bus

You think it's something like this?

Nothing of the kind!

The meaning is the following:

To unintentionally drive a common route. To turn on the mental autopilot and arrive toward a location other than your desired destination. For example, if you set out to drive to the store, but after a few minutes find that you are halfway to your place of work.

Example:

If I'm not careful, I end up driving the bus to work on Saturday mornings.