You won't find people willing to take jobs in construction, plumbing, electrical, farming, etc if they can choose to do nothing instead.
Citation needed.
Especially one that takes into account increasing automation and software, not merely medieval society needs, and which solves a large part of grunt jobs.
Besides, there are people genuinely love working in the fields you mentioned: construction, plumbing, electrical, farming, and that would do them over nothing. Especially with a pay increase over UBI, so that they do them as a choice, not merely because they're forced to not starve.
Maybe not so many for things like sewage cleaning, garbage disposal and burger flipping, but again a pay increase over UBI would help with that too.
This will also help compensate those jobs according to the value they offer to society, not according to how many people starve and can do them at piss poor compensation to feed themselves.
There is no citation needed to show that society would collapse if essentially all manual labor stopped overnight. To suggest otherwise is silly.
To suggest what I proposed equals "all manual labor stops overnight" is taking for granted what you were supposed to prove.
That's exactly what we were arguing about, remember?
"We throw them in jail if they don't"? We don't do that presently.
What we're talking about is "in addition to anything they earn, they choose the disposition of $X/yr", for various values for X. If X is $1, clearly everyone is still working. I agree with you that the $40k figure you cite downthread is extremely likely to be higher than we can support. I think there are intermediate values that might work substantially better than $0. Based on toying with numbers that I've done in the past, my guess is that the optimum value $4k and $9k/yr (though I'm not all that confident in that and would probably want to see it ramped up gradually). If you claim that this would mean "essentially all manual labor stopped overnight", that certainly needs a citation.