So let me just add a couple things in response.
First--tangentially--I never really understood the obsession of the right wing with the impact of the NYT. It's paid subscription base is about 220,000....with a'readership'about twice that.
Fox news averages 2.37m viewers--and that's just in prime time--doesn't count the rest of the day. In other words, six times as many people watch Fox News in prime time as read the NYT at any time of the day.
Anyway, on your main point about unions vs. corporations, here's the important difference:
"Federal rules require unions to publicly disclose all political spending and itemize payments over $5,000 with the date, name and address of the recipient, and purpose of the payment. Critically, this includes spending done through third party groups.
Corporations are under no similar blanket federal obligation to disclose their use of corporate resources for political purposes. They do not have to disclose political funds they route through other groups such as 501(c)(4) “social welfare” groups and 501(c)(6) business associations – and these tax exempt non-profit groups also are not required to disclose the source of their funds."
As I think I've done before, I can not recommend highly enough the book Dark Money by Jane Mayer.
And finally, the last point is this: do you, like me, support some limits on 'special money' (whether union or corporate) spent on elections, or not?