Fundamentally the union should be getting the workers a fair deal for their labour (conditions and wages); once the union starts interfering with the technical aspects or blocking labour saving investment it quickly sours the whole arrangement.
It's not even about blocking investment, they just want to make sure the employees still have jobs. You can invest if you find something else to do with the employee.
It's not even about blocking investment, they just want to make sure the employees still have jobs. You can invest if you find something else to do with the employee.