I've got other gripes about UBI, and especially about pinning the hopes of a "purely voluntary (but with asterisks)" workforce onto it... but there really is no telling how we would behave if we tried this experiment.

For every study suggesting that Hardin's "tragedy of the commons" is actually a legit thing (even though Hardin was later exposed as an academic fraud who fabricated his theory because of his white supremacist, eugenicist political agenda), there is another study suggesting that we're actually historically really, really good at managing commons and that perhaps capitalist framing only gets in the way of the cooperation that we're predisposed toward.

There's even one that came to mind specifically about sanitation workers: https://youtu.be/fe-SZ_FPZew?t=2403

There's also not any evidence that we settled into our modern capitalist model due to any sort of societal optimization. All of the theoretical reasons why an economic abstraction may be an advantage over a social gift economy don't really hold up when you look at historical or contemporaneous accounts of actual gift economies. It seems like the only reason we ended up with this model is because it was advantageous for several waves of wealthy rulers who needed ways to translate their violence-based power into legal power or else lose it.