On commutes it is very unusual. On weekend rides, people can't resist grabbing the wheel of a guy 6'-6" and 240 pounds cruising the flats at 20. I don't usually mind, but I give a lot of space myself. Scary when I do it, me thinks.

When I occasionally pull out a recumbent bike, fun thing to do is follow a pack of roadies 50' back, and watch it slowly disintegrate as they try to stay ahead, falling off the back 1 or 2 at a time.