Going onto the IdiotsInCars subreddit, it's kind of shocking how commonplace it is for people to undertake other road users by speeding past in the slow lane. It's already more difficult to merge back into a slower lane because you have a much bigger blind-spot (and have to twist your neck a lot more to get a good look), so it doesn't make it any easier if you have to expect that people will be speeding to undertake you.
