I think the idiots are the planners who devised the moronic one way system. They only considered traffic flow and ignored the needs of cyclists and pedestrians.
There's a one way street near to me which used to be two-way until about a decade ago. There was a persistent problem of vehicles using it as a rat run to avoid the queues at the traffic lights at the top of Easter Road. Making it one way has reduced that misuse of the street, but has encouraged residents to park on both sides, narrowing the carriageway. Also rat running still takes place in a northbound direction, as you cannot turn right into Easter Road from London Road (heading west).
However as it is generally quiet outside peak times, I cycle the wrong way up this street all the time. Not only do avoid the hazard of left turning vehicles at the top of Easter Road, I can also turn left straight into a bus lane heading east. So illegal contraflowing by this cyclist (and others) is far safer than following the law. If a vehicle arrives at the top of the street, I pull over into a gap between parked cars, or as close as I can manage, to let them past. No-one seems to mind in the slightest.
This is such a good cut-through for cyclists compared to the alternative that I'm minded to ask the Council to make it a legal contraflow for cyclists. (I'd go further and argue for the removal of through traffic altogether by judicious use of bollards, but let's be realistic).
So, in short, cyclists who cycle the wrong way up one way streets are not idiots. They are merely demonstrating the idiocy of the way our road network is managed.