I seen a few in the US, usually on Harley-Davidson. People who only get the bike out to be seen on group rides on memorial day and the like. In the US people can ride just about anything on a learners permit so it is always a recipe for disaster. Two examples I can think of out of many are my first ride with a group, there was a guy on a 1200 Sportster, he kept drifting towards other bikes, ran into the back of a couple of people, I just stayed way back out of his way. When we stopped I told him to stay away from me to prevent a premature ending to his life, he went home at that point.
Another group ride in the Georgia mountains and a female rider on a newer version of my bike, riding on a learners permit was really struggling in the bends, at one point she was drifting towards the drop off so I rode up the right side between her bike and the side of the road, took my left hand off the bars and placed a single finger on the end of her handlebar, just enough pressure to get her through the corner. We stopped and had a talk about steering and she was fine after that. She admitted she had frozen up on the corner and would have ended up over the edge. She turned into a good rider over the following months. There were a lot of women riders on Harleys in GA and in general they were excellent riders, the worst riders were usually men who started riding later in life.