Then there is the rank amateurs among us who have demonstrated VRS (probably more like incipient VRS) quite by accident. (accident meaning inadvertently....)
The FAA requires a demo of VRS as part of the CFI checkride and as a part of the annual part 135 Air Taxi checkride.
The real key is to know what it is, when it can occur, what the warning signs are, and how to recover to normal flight. It would appear to me professional helicopter pilots should be well acquainted with VRS and have experienced at least a mild onset some where in their training.
Longline work is one situation that is likely to put an aircraft at risk for the onset of VRS should the winds be light and variable.