Kickstarter's in the US, no? Did you check out that WP link? I don't mean this as a "did you even read the article" jab, but you mention Labour, but this is about the US and the laws in the US mandate that those working under union labor agreements may be required to pay dues, yes, but may also be allowed to (effectively) specify that their funds may not go toward (most forms of) political spending, but only bargaining and member services.