I suppose the act of undertaking isn’t dangerous in itself, especially if the driver of the car in front is driving along totally unaware of anything around and fixated on staying in the lane they’re in, they won’t know it’s happening until it’s already done. I’d say you over rate the quality of driving in the U.K. though, they may well think they’re good drivers by obeying their interpretation or the Highway Code, it’s when they don’t obey the laws of physics that the accidents happens.😀