These are examples of workers leveraging their collective strength to do something that putatively a majority of workers support (modulo corruption/bad leadership of course). Shall I now give you the endless scroll of management doing all of the above and worse? Yes, union workers have a modicum of power to impact company operation, but it's not built-in to the concept of collective bargaining and indeed your Google example "attempted" to do something; management can simply do it.
> it’s not a stretch to imagine a union attempting to change Wiki policy to achieve political goals. Wikipedia is a public good and I would highly oppose this.
Wikipedia is not a "public" good. There is no mechanism preventing Wales and co taking it whatever direction they want.
> Co-ops are a better model for workers who want to join a company where they have full democratic control.
Co-ops are indeed great, but Wikipedia is not offering to become a co-op. You are arguing for "designated powers and limits" on one side only. If you're "pro-union" you have to accept that this grants powers to the collective, and if you start putting brakes on it without doing the same for management, it's anti-union.