Quote: "That's democracy surely both have the same options - if you don't agree you can act either sell the shares or leave the union - its the same. Once you pay in to Unite you have no say in how Big Len spends it.'"
If you read my post again you'll see that there is a difference.
You can be a Union member and opt out of the political donation - even if the majority of Union members opt in. That is in stark contrast to being a shareholders. If the majority of shareholders agree with giving a political donation then the minority have to go along with that decision - or leave.