The question is then how often would this occur at uncontrolled aerodromes?
If by "this" you mean traffic using different, crossing runways at uncontrolled aerodromes, and transmissions being garbled, over-transmitted or not heard due to finger trouble: Quite frequently in my experience.
We should also beware the 'false dichotomy' risk: One pilot having to be entirely in the right and therefore others being entirely in the wrong. It may be that a pilot beginning a take-off roll should be waiting, in accordance with 91.370, for an aircraft landing on the crossing runway. But if the first aircraft is using the most into wind runway, it is also true that the pilot of the aircraft landing on the crossing runway shouldn't be doing so unless, among other things, satisfied, after taking into consideration the other traffic, that it is safe to land on the crossing runway.