Flugpants.
I think you will find that in this case, as it inevitably is, any contract will have been agreed between the Tour Operators and the coach company and not with the coach drivers themselves. The workers are perfectly entitled to take industrial action as they see fit and the coach drivers at PMI, MAH and IBZ are no different to the baggage handlers at TFS - they know exactly when to act to cause maximum disruption!
As for our German colleagues being ultra-clever in booking taxi's, I operated one of the first flights to arrive at PMI after the industrial action had started, arriving just after midnight. All our pax were taxi'd to their resort at some considerable expense to the tour operator but obviously as the strike started to bite the demand for taxis considerably outstripped supply with the inevitable outcome.
I agree that the bully-boy tactics and intimidation which appears to have taken place was out of order (but did remind me of the Miners vs Thatcher bout a few years ago!!)_I also understand that the negotations lasted only 10 mins and the offer on the table, 15%, was rejected and further action is being planned for next week. The coach drivers allegedly want 17% which seems awfully close to 15% to be the reason for all this mayhem! Ho Hum!