I already have quite enough entities "democratically" deciding how to represent me or spend my money in ways I oppose, and I don't want another. Do not presume to speak for me or count me among a number of "supporters" of any cause without my explicit consent. The right way to handle any kind of lobbying is "we're thinking of supporting this cause, here's an easy link if you'd like to support that cause, and we'll only speak for those who agree"; that would still allow a union to facilitate collective action without presuming to speak for everyone.
There's a huge difference between (for instance) "let's collectively demand better working conditions, better benefits, and equitable treatment" and "let's lobby the government to make it illegal to work on software without being a union member". I don't care if 53% of a union favors the latter or not. Unions can and do engage in regulatory capture.
Like any concentration of power, unions can be used for good or for ill. Propaganda would have you believe they're always bad, and pro-union folks would have you believe they're always good.
Both can be true:
- A union lobbies better for me than my employer.
- No lobbying represents my views better than either employer or union lobbying.
A union lobbies better for me than my employer.
Those interests may or may not coincide with yours.
Because you may not perfectly agree with union lobbying, it's better to leave corporate lobbying unopposed, which will almost certainly leave you (and the entire working class) worse off?
But I do agree that there is no way companies would chose to refrain from lobbying if the option was available.
This also has a number of other benefits to democracy, notably that social science has shown that our allegiance is to those who we are in closest proximity daily with (i.e. representatives might actually represent their constituents instead of the political class) and it disincentivizes gerrymandering (if you're gonna shove all the black people in one district, you're gonna be living with them).
There are concerns with logistics and security when it comes to electronically submitted votes for elections (i.e. e-voting) but this sort of a solution side steps any concerns like that, heck it could be voting by show of hands over a video chat.
I do disagree with the gerrymandering portion though, I think the US really needs to adopt a proportional representation system (I'm partial to MMP) which would just make any attempt at gerrymandering irrelevant, sure you can win a particular seat if you gerrymander, but the amount you can effect overall representation would be quite minimal.
The corporations you work for the the exact same thing (lobby for things they want) and it's rarely for your own benefit. The difference between a union and a corporation is that unions are democratic organizations. Good luck voting your boss out of their job. All you can do now is quit and find a new job, which for a lot of workers isn't easy to do.
This is the argument used in the recent Janus ruling of the SCOTUS. It's part of the last 40 years of anti-union propaganda shoved into our faces by corporations.