One turning right at a roundabout where an oncoming car was travelling too fast to stop and give way to me
Round here, they don't generally give way to cyclists on roundabouts at any time. Even in a car, when turning right at a mini-roundabout, you generally have to stop and wait to be sure that oncoming cars really are going to stop*. It's a combination of overlooking tiny roundabouts thinking they're T-junctions, not knowing the rules and a bit of "f... you, I'm not stopping".
*you'd fail a driving test for undue hesitancy but you wouldn't lose your licence for it, and it's saved me a few times