I'll try not to be like fauci and say that every piece of evidence is anecdotal, but I don't see any. Yes the cases are below the crazy predictions. Yes the Healthcare system has remained fully functional. But those aren't evidence that social distancing did anything.
To me the biggest evidence that social distancing has been useless is California vs New York. California's shelter in place order came only two or three days before new York. There's simply no way 3 days makes that difference. Especially when you consider that the virus most likely hit the west coast first.