Employee Free Choice Act question: Why can't we have it both ways?

Business interests are opposed to the union card check system because it "deprives" workers of an anonymous ballot. When you sign a union card, your signature is there for all to see, they claim. This is why many officially oppose it. It violates the "privacy" of workers, they insist.

Why can't we do both? Why not have a confidentiality agreement between a person who signs a union card and the labor union, an agreement that excludes the employer from viewing the cards in question? Why not make it so that the only one who could demand to see the cards is the NLRB alone?

With a card check system, a union is recognized the time a majority of workers in a workplace sign union cards, but that rarely is the case. Employers challenge it and force a formal NLRB union vote that gives employers more than enough time to pressure and coerce workers into refusing to unionize. However, in order to get a union decertified, all that has to be done is, ironically, a card check system where once a majority signs on, the union is automatically removed.

It is easier to remove a union than install one.

What I'm saying is why can't it be both ways?