Well, contract workers are literally treated like dirt. Doing problems? Not working enough? Damage? Contract terminated, we do not need you anymore. This is often exploited all around Europe, when companies / employment agencies hire foreign people for contract work (mostly for physical labor in warehouses and construction yards). And then after months of hard work, they end up without money or even without passports.
It is a different with regular employees - they cannot fire me on spot, unless they could prove theft/deliberate damage/physical assault. Of course syndicate can "protect" you, but I wont give 15 of my poor salary each month for them, I rather go for a beer or two with that money.
But I think that if we would go for a strike, we would end without job. Hm, lemme try that