So how would a business communicate that it believes the employees' livelihoods are threatened by a law? Is it just flat-out illegal for an employer to tell people that lawmakers are about to put them out of work?

Imagine a totally different scenario, where the government is about to cancel a defense acquisition program (like the F-22, which was cancelled). Could Lockheed-Martin bring this to the attention of the employees? If so, how?

It would probably do so by advocating against the policy in the public forum where their employees weren't specifically targeted as the audience.

I think the meat of the issue is that Uber doesn't get to decide Prop-22, it's a decision by California and if you want to sway CA talk to CA. If you legitimately think your business and all it gives to the economy and community would be destroyed by that proposition then tell that to all the residents of the state - targeted messaging to your employees is just all sorts of shady and, whether intended or not, it will leverage the power imbalance of the employer/employee relationship for some people.

It's pretty much the same reason you should look elsewhere for love - there is an existing relationship between an employer and employee - bringing other relationships into the scenario just makes things murky.

Well, your idea actually produces an effect counter to what I would assume your preferences are:

Large employers, with a lot of market power would still be able to communicate to their employees via public channels. Small employers with very little (employment) market power would be basically muted.

Is this what you're looking for?

It's better than what we have now - I think the US needs to take a very serious look at purchased speech in the long run but there are a whole bunch of problems we'd need to solve for that and I've been told by the PM that that's out of scope for this project ;P

Employers can still share internally (same way public interviews can be shared as a heads up)

That would still be biased heavily in favor of large corporations; NASDAQ-100 CEOs get a lot more interview requests than local bakers.

Seems to me the heft of the problem falls in forcing drivers to either explicitly consent to agreeing with the platform's views by selecting "Yes on 22" or to communicate their ambivalence by selecting "OK" in the dialogue that is presented to them in the driver app.

If Uber just presented an explanation of the issues and allowed drivers to decide for themselves without any way for the platform to track their decision, no problem.

I may be in the minority, but it seems to me that a 'threat' has to be something more than simply recording whether someone agrees or disagrees with a given position.

I'm not suggesting that there's any threat, implicit or otherwise. But why should an employer (or contractor) be allowed to register the political sentiment of their employees/workers as part of the normal course of business?

Well, this thread is about a lawsuit, where the law in question refers to a 'threat'. I'm not sure about the morality or ethics of this question, and it seems like it would really depend a lot on the framework you use to analyze the question (as well as what the long-term outcomes are likely to be).

Pretty easy. Just inform your employees about the law and its implications. Don't tell them how to vote or threaten them to vote. Your employees aren't sheep that you have to herd. If they think the law will threaten their employment then they know how to vote even without any pressure.

I don't think that should be illegal. I don't even know whether or not it is illegal currently. I posted what I wrote just because the extreme example came to mind, and it gave me a laugh.

To seriously answer the question: I don't know where or how you'd draw the line in the sand.