Any universal income would eliminate or severely diminish the survival factor of work. The reality that the individual must have work to support him/herself. People accept less than optimal, for them, work situations as a result. If people have options - such as a guaranteed ability to survive, no matter how minimally - they have the power to refuse some situations. That would diminish the bargaining power against the individual worker of all who currently employ people at or near the UBI level.
I don't think this is what will happen though. Rather by eliminating poverty traps and subsidizing low wage unskilled labor, it should lead to near-full employment. In a world like that, BI doesn't even need to provide enough to survive long term and perhaps shouldn't.
Ideally BI is not a slacker's charter, it's a subsidy for employment. After all, somebody has to pay the taxes that fund BI in the first place. However I do agree that it could also increase worker's bargaining power. If the increased demand for unskilled labor created by the BI subsidy for employment increases the quality and value of the work available. For example right now it might not be economically viable for a craft carpenter to hire an apprentice, but BI could relieve them of the burden of having to offer a completely livable wage and the resulting job might be more attractive than flipping burgers or janitorial work.
It's a complex set of variables. My concern with trials is that by only including a small sample of people in a generally non-BI economy, the effects of BI on the rest of the economy just can't be gauged. In particular the effect by which it subsidizes employment may not become visible at all.
There would absolutely still be market share/place for unions. My guess is they simply refuse to tolerate anything that could even possibly diminish the status quo.
Not necessarily. It would depend on whether you receive UBI while on strike. If you do then strikers could threaten much longer strikes because the UBI would stretch their savings a lot longer. That would give the unions more leverage. Possibly too much leverage.
Of course you would get UBI while on strike. That's the "universal" right there.
It's not a particular change in Finland, though. There are comparatively many strikes in the country, many of them illegal (or, to be precise, breaking collectively bargained contract that is valid applicable law). This is partly due to the fact that unions can raise money tax-free and pay to striking employees tax-free.
