> I also believe a german union would have a hard time to force a company to hire people that are not needed for a project or even influence who the company can hire.
A German union has to make sure that it doesn't negotiate anyone into uncompetitiveness. If you negotiate for too high a pay, or absurd things like useless jobs, the company gets outcompeted and all those jobs vanish. In the US some unions seem to get around that by either being big enough to cover enough companies (construction), or the companies themselves are local monopolies (e.g. railway). That doesn't work for most European projects because Unions usually don't span borders, but you can always get a construction company from anywhere else in the EU.
A German union has to make sure that it doesn't negotiate anyone into uncompetitiveness. If you negotiate for too high a pay, or absurd things like useless jobs, the company gets outcompeted and all those jobs vanish. In the US some unions seem to get around that by either being big enough to cover enough companies (construction), or the companies themselves are local monopolies (e.g. railway). That doesn't work for most European projects because Unions usually don't span borders, but you can always get a construction company from anywhere else in the EU.