It's all true, but in practice, in the US, and I strongly suspect in Switzerland as well, there are all kinds of means-tested transfers, such as unemployment su

It's all true, but in practice, in the US, and I strongly suspect in Switzerland as well, there are all kinds of means-tested transfers, such as unemployment support, so the first equation is actually U(job income) - X > U(unemployment support) which (unlike the concavity issue) is a first-order effect, and keeps millions of people from working. I very much suspect that replacing that with basic income is going to bring more people into the workplace, not the other way around -- as long as the basic income is kept reasonably small. Now, keeping it small is another matter.