The problem is that some people are being paid too much to be meddlesome.
If you have a bullshit job you are paid to do nothing. If you have UBI you are paid no matter what you do. Somebody who has to not get fired cannot do anything other than sit in their chair and do their bullshit job. They are actively removed from the pool of useful laborers. But somebody who is paid regardless can choose what to do. Yes, they can watch TV all day. But they can also do something that isn't bullshit.
https://www.newarab.com/opinion/saudi-workers-enraged-five-t....
But there is absolutely a difference, which you already mentioned: Seat in chair for 8 hrs.
They might be spending it watching YouTube but they can't volunteer or start a band or do whatever they want.
With UBI there is no nominal expectations so nobody does anti-useful things like adding paperwork to justify their existence.
The key part of the book for me is that people really truly want to work and be useful. Case in point why people accept teaching roles despite the bad pay. In fact, people will volunteer to do these things for free. So why should they get paid at all?
Jobs that are useless can't get people to stay for any reason other than money. In essence, because it is useless it pays well.
One option (UBI) is to pay everyone and then they do what they feel is most useful.
But the incentives for doing useful work are not there, since enough people are willing to be paid in good feelings instead of salary. So if not UBI something needs to change to make real useful jobs worth it
This is interesting to me and I wanted to dig in more. You seem to imply that Qatar has some form of UBI, but I can't find any source to that effect.
[1] https://www.psa.gov.qa/en/statistics/Statistical%20Releases/...
[2] https://www.zawya.com/en/economy/gcc/saudi-citizen-account-p...
If the problem is that some people are being paid too much to do nothing, the exact opposite solution is to pay everyone too much to do nothing. I'd be 100% supportive of UBI if that meant paying everyone in the world $2 a day, but what UBI actually means is giving exclusive in-groups more money than the median global income for free. We see exactly what happens in the gulf oil nations like Qatar. The citizens outsource all their real work to an out-group that doesn't receive free money, so they have absolutely no incentive to improve working conditions.