Because the idea of UBI is that it's universal basic income, which keeps you fed and a roof over your head and other such basic things. I heavily doubt that the

Because the idea of UBI is that it's universal basic income, which keeps you fed and a roof over your head and other such basic things. I heavily doubt that the mentioned 30-40% of the population are okay to live with the bare minimum without having any interest in doing something to change that; that's only possible if your actual income allows for more than that, which seems to be the case in the Saudi States.