Cutting corners

Hey - its a bike not a Hummer.Soap box time...Whats the go with riders cutting corners on mountain roads? I saw some guys doing this on weekend for no good reason that I could fathom and it reminded me of how often I have seen this of late. Perhaps its just laziness however my first thought whenever I see this is ' don't do that you idiot I don't want you to crash and take me with you' . If