I think if you're looking for proof you're setting too high a standard. But Seattle's experiment hasn't gone well AFAIK. Higher wages = less hours to go around = less money, less economic output, less investment, and so on.
"Relative to outlying regions of the state identified by the synthetic control method, aggregate employment at wages less than twice the original minimum—measured by total hours worked—declined."
On the other hand, taxing restaraunts with unhealthy food and forcing that money to go to low income workers maybe isn't so bad. I think NYC taxes soda directly for instance. Imagine if they forced that money to go to workers.
1) Investors might earn too much return on their investment and wage inequality is high.
2) This study ignores downstream effects that result from the lower returns for ongoing/new investment. Since they’re now paying more for labor and selling less, new investment and upkeep has a lower return. Less store upgrades less new restaurants less expansion and so on. In the short term though, of course wage growth (inflation) feels good.