When you automate the entire economy, salaries also go down toward zero. That's even part of what allows prices to go down.
So, did workers become richer or poorer on the process? It's a 0/0 situation, and the answer to that question will depend entirely on the path both curves take into 0. But UBI makes that all irrelevant by adding a minimum bound on the numerator. For the purpose of fighting the problems of automation any reasonable amount will do, it doesn't matter that it looks too low today.
But of course, there are other goals that one can reach by UBI, and none of the above apply to those ones.
1 - There are obvious exceptions, some things are truly limited, and some things are limited by the government, culture, or other such forces. The cost of those are the real limit that will say whether the UBI value is too low, not today's cost of living.
Not at all. There are still plenty of limited factors in the production function. The capital itself isn’t unlimited, so you need to price in opportunity costs for using it. Much of the capital needs to support people providing services, so you’re still limited by the labor force for doing things that people prefer having humans do, like knowledge work or personal services.
And then you have to contend with the fact that resources are finite and capacity to extract them is too. We’re a very long way away from automated labor being so effective and so ubiquitous that it fully realizes all the benefits you’re talking about.
In the foreseeable future, it’ll probably be rather unpleasant as shitty robots replace competent humans, meaning the quality of services and products we get are bad but the good versions are prohibitively expensive. And the jobs making things start going away so nobody has the money income to get quality versions of things.
Even if this happens for most other needs / products, housing isn't a commodity, and I expect won't ever be. It will generally be demand driven in terms of relative housing costs, and if you're of the mindset that inequality in and of itself is the problem, the lowest tier housing will never be enough, no matter how sufficient.
Which will just lead to a larger part of newly disposable income being spent on housing.
We already know people pay based on what they can afford.
Unemployment isn't our major problem right now. The problem is that the jobs available for many people pay very little. Back when I made $18K/year, that extra 10-15K/mo would have been enormously helpful. I certainly wouldn't have stopped working; I would have paid down my credit cards and had an easier time training myself to write software.
In the meantime, with most people having at least low-paying jobs, we can start with something more modest.
For the combination of higher taxes and UBI you need to look at how the net effects vary across the population. This isn't easy to do without understanding the taxes, and those tend not to be emphasized. (Yang's proposal has a big hole in it; the taxes aren't enough and he relies on economic growth to make up for it, which is a common dodge many politicians use for big proposals. Not that economic growth can't happen but it's not that predictable for something that hasn't been tried. You don't know when the next recession will be.)
In a zero-sum redistribution scheme intended to reduce inequality, if you're of average or high income you might not directly benefit at all, but that's no reason not to support it. You buy fire insurance for the worst case, not because you plan to make money at it in the average case. You get security from it that's not shown in the estimated average payoff.
It's unsustainable nonsense, and incompatible with any sort of long-term stable future. The economic battery whose poles are the first-world consumer and the third-world sweatshop worker will run down eventually, and it's long past time to start thinking about how we'll adapt when that happens.
I fail to see the major disaster if it becomes somebody else instead.
E: to the downvoters, look up how money gets "printed" in the USA
The reality is if we end up with a large amount of people that are not working then our economy is going to be totally hosed because it runs on consumption. If people don't have the money to consume then it just stops functioning.
Giving people free money is like putting a bunch of taped together printer paper over a hole in the wall and calling it "fixed".