I found myself lining up at a traffic light stop line alongside a single-decker bus the other day. I was there a good 20 seconds by myself when the bus pulled up right alongside me so that we were both side-by-side on the line, as it were. I was obviously quicker at moving off when the lights changed but it became clear straight away that the bus driver was committed to overtaking me on the junction so I backed out of it as I didn't want to get squeezed between the bus and the pavement after the junction.
In fairness, the junction is probably about 20m across so there's a gap to pull off that move if you're driving a car, but it was an aggressive/inconsiderate move for a bus. It just so happens I wasn't in a rush so I had no inclination to compete with the bus to keep it behind me just for the sake of it. But it was a disappointing encounter considering bus drivers are 'professional' road users. Fwiw, isn't an advanced stop line at this junction.