They can vote their bosses out and they usually have statutory civil servant protections as well. When government employee unions negotiate with their employer

They can vote their bosses out and they usually have statutory civil servant protections as well. When government employee unions negotiate with their employers, they negotiate with a political actors who, if they act right, get support from the union for their next re-election. The incentives encourage political actors to bend to the unions will to receive donations or endorsements in their next election. Typically this is called a conflict-of-interest.