Why $62500?

The participants should be voting on how much to take from those among them with the higher incomes. I mean--unless we're assessing how UBI might work in a country without democracy.

Democracy is not a free pas to vote anything, especially if it is negatively impact some people, otherwise you justify gang rapes as a majority decision.

Sure, but it's tough to imagine in today's climate that a majority of voters living only on UBI would vote to maintain or lower the amount of money given directly to them from the top X%.

We already have the issue today but it's not quite so direct.

This is a huge problem with UBI. Maybe people will have to make a choice, either live on UBI or vote, but not both - it is immoral to vote for your own benefits.

tbf since their targeting was low income neighbourhoods, one can assume the higher income neighbourhoods would have contributed some of the share.

A fair experiment would have at least stripped away all the other state funded benefits UBI supposedly replaces, but I guess 'UBI is good for the spending power of single-income couples but leaves the poorest people much worse off' wasn't the headline the advocacy group was shooting for...