Not sure why some are being harsh. No one else ever had a car or bike just appear out of nowhere? I had a close call the other day, an idiot tailgating me when the speed limit changed from 40 to 30, so I indicate to change lane, check mirrors, move over then suddenly there's a bike right behind me which came from nowhere, which I probably just missed, the idiot was speeding. I've also had plenty of idiot black cabs who just stop suddenly in the middle of the road to pick up or drop off passengers, or make sudden u- turns amongst loads of other awful driving. Unfortunately for OP you got caught out by these idiots who dont have any respect for road etiquette's.
The only time the things you mention are a problem is if you are not driving properly yourself.
Its not harsh, its just a fact.