Well, I agree with most of it. The part where people stop before the stop line may have to do with entering the junction at top speed (50km/h) as soon as the light turns green (begin acceleration as soon as it is yellow), but is most often not the case.

As for the abrupt breaking, I often noticed that there was a police somewhere up ahead. Definitely not an excuse, but may explain some of the cases, in case you were wondering.