The basic laws of supply and demand are distorted a bit when much of the business is not strictly necessary, but something of a "delete option". So [In the UK],
Offshore is necessary - there is no other practical way of moving bears around
Police and HEMS etc is probably necessary (but note in the USA local forces regularly seem to lose their Air Wing due to budget cuts and some HEMS charities struggle)
Pipeline and Line Inspections
A small amount of aerial work
Some Aerial Filming/Photography
Everything else could be done some other way (possibly slower & less enjoyably but it could be done)
This substantially weakens any industrial "strength" I suggest. If you add to that there is rarely a problem in finding a pilot, then "withdrawal of labour" doesn't seem to me to be scary for operators or customers. When offshore pilots withdrew their labour to go plank, the rates went up pretty sharpish, but that doesn't seem to be happening much now.