If I had a choice between e.g. $3000 monthly for working and $500 for staying at home, it would feel very different from choice between $3000 for working and $0 for staying at home. I could probably translate the "very different feeling" to better position at negotiating either higher salary or better working conditions.

It's not obvious whether I could translate it exactly to $3500, or whether the additional money would be split between me and my employer. Please note that the labor market behaves a bit differently from typical markets, because when you pay people more, their free time becomes more valuable. For example, if you paid me 10 times more money than I make now, a likely consequence would be that I would work for you only shortly, and then enjoy an early retirement. (An effective altruist would keep working, though.) By increasing the market price, the supply can go down. So in some circumstances it could create a spiral of skilled people demanding more money, then leaving the labor market soon, which would increase the salaries of the remaining ones, etc.

Not necessarily. That's why I brought up the example of basic income serving as a permanent strike fund to help employees demand higher wages. Employers can respond by meeting their demands, and/or automating more quickly, etc. Then society can respond to increased automation by increasing the basic income. Or not. I won't talk about society's transition into a gift economy here because that would take too much space.

I know you're trying to paint Basic Income as a subsidy to employers, but it's really not like the Earned Income Tax Credit. At all. I'll continue this in the LukeASomers thread.