The main point of UBI isn't “more money solves problems”, it is “replacing means testing of benefits with unconditional benefits removes adverse effects of the rapid clawback of benefits with increasing-but-still-low income”.

Giving individuals money without changing the policy context doesn't actually test the mechanism of action proposed for UBI. (It does, arguably, test the mechanism of action of some proposed private charity [or business-linked] alternatives which do involve cash transfers and don't involve changing the public policy context and incentives, but that's a whole different issue.)