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It's not just people on the left proposing it, it is people across the political spectre.
There are a few proposals on how this would be funded, I'm not totally convinced yet that they would work completely but I do agree with the OP that we do need it, or at least we need to have a proper debate on it.
The trials that have taken place so far all showed pretty good results, but funding was not an issue there as the tests were small and localised.