I mean, most employer policies never get any kind of vote from any subset of the employees, so I'm not sure why I should be so outraged about this one in particular when it seems to be usually to workers' benefit.
Clearly they don't think it's to their benefit, or else they wouldn't be trying to decertify or deauthorize it.
They are, just not directly, because the direct process for decertification or deauthorization is both highly risky (if caught, they could lose their jobs), and also pretty ineffective (the NLRB has a habit of overturning election results, rendering the whole process moot.
So, they use other tactics - hence the increasing support from union members for anti-union lawmakers. Political pundits often write about this as a "paradox" of union members voting "against their own interests", but it's actually pretty straightforward once you remember that union members are individuals who may or may not actually support the interests of the union that they belong to.
It doesn't sounds like they want any of those so-called benefits. As explained below, the data suggests that if members could feasibly decertify or deauthorize their unions entirely, they would.
Remember that, nationwide, only 7% of union members ever cast a vote in favor of their union. That means less than 7% voted against it, and the remainder never had an opportunity to vote at all.
It's not surprising that, in the absence of a safe way to decertify or deauthorize, some portion of the 86+% who never had the opportunity to vote supports laws that give them the next-best thing. (It's not just right-to-work laws, by the way, though that's the most frequently discussed at the national scale and therefore the most frequently polled).