To me, a useful definition of the "far"- prefix would mean that a small portion of the population supports it. I think it's clear that a very large, if not majority, portion of the US population supports the above mentioned measures, however, their federal votes are gerrymandered so that it's not actionable on the federal level.

Legalizing marijuana most definitely has majority support in the US, but few states have done it. But I wouldn't classify legalizing marijuana as a far left position.