I'm very socialist actually. I just think that with a good socialist government, unions are not needed as such because the national law already protects workers' rights. I find it a bit 'off' that each class of labour has to fight for their own rights separately. That shouldn't be needed (and really isn't, where I live). It also causes a lot of uproar, see France for example where a strike is just tuesday. Employee rights are strong, but the public is heavily impacted all the time. Better to just handle this on the government side. This is why I was a member of the socialist party but not of the union in my workplace (I'm no longer a member because I moved countries and can't vote where I live).
Note: I'm not living in the US obviously :)
I do say a balance because of course we're not living in a communist state. So even with a socialist government there is still capitalism. Just not unrestrictedly so as it is in the US.
I'm not sure how it works in the US but in our company the union is many bitching about stupid stuff like breastfeeding rooms (when there are no women who bring their babies to work anyway - they just work from home after their 6 months maternity leave). All our basic rights are already sorted. We can't work too many hours, we have unlimited sick leave (though of course validated by a doctor for long absences), we're entitled to a lot of money when fired etc. But this is all national law level stuff. Not industry level.