Actually if there are any people to blame apart from the guys who create these contracts, its the old pilots. They were already in the union and had the chance to fight it. But since most of the older pilots are captain or SFO they don't care about FO's.
Good example is easyJet Lisbon base. After the industrial actions the contracts improved significantly for captains and SFO's. Guess what has changed for SO's and FO's? Nothing. Because there weren't any at the time.