Um, how do you suppose people change lanes?
I think the author's problem is more along the line of how some people pull into a lane, being a "if I fits, I sits" way of looking for a suitable gap (as well as being only slightly better than cutting someone up), as opposed to looking for a gap that gives sufficient room for braking distance both in front and behind.
On the motorway I often encounter this situation with people pulling in front of me, giving me the choice of riding their bumper (just by maintaining speed), or brake to give safe distance between myself and them, then that happens three times over and I end up overtaking several cars just to find a safe spot without having to regularly slow down because some people drive like jackasses.
I wouldn't mind it so much if they pulled in front of me because they have to turn off shortly, but some people do it as a matter of course.