I'm sure the company pressure is far, far more salient in 99.9% of cases than the unionization pressure, but I think for any collective agreement like this we oughta shoot to eliminate as many sources of coercion as possible. I can definitely imagine certain industries where it would definitely paint a target on your back to oppose unionization.

Seems like the solution is to just allow ad-hoc anonymous votes upfront?

I appreciate you walking me through this though!

Yes, but then the company complains that something it doesn't like is being organized in its property (the workplace) using its resources (employee time, space and electricity for the vote collection/tabulation etc). Plus the people trying to organize the secret ballot are easy to identify.

It's considered perfctly normal for owners of a company to delegate their power and responsibilities to managers, but whenever employees try to delegate things ao tunion 9/10 times the owners scream and cry and allege dark conspiracies.