>UBI-related experiments consistently find evidence that no participant responds to UBI experiments by dropping out of the labor force.

I'm not familiar with the details of these experiments but the first thing that strikes me is that this cannot be experimentally tested without guaranteeing participants a lifetime of UBI. They don't drop out of the labor force because they know it's temporary.

You wouldn't quit your job if you're only promised 2 years of UBI, because the cost that resigning has upon your future employability may be greater than the money from the UBI experiment. Or if you did quit, it would be to make a gambit (such as going back into schooling or training) that will leave you better off once the experiment is over.

The only reliable experiment design would be putting a few million per participant into some guaranteed annuities fund.