Because putting people into space is pretty useless. It certainly doesn't accomplish any economic purpose. The only scientific purposes are related to answering "what happens when you put people in space?" which is a circular justification for the program.
SpaceX has been operating for 13 years and have yet to put a single person into orbit. They have yet to even succeed at their stage recovery mechanism, which is the cornerstone of their cheap access to orbit plan. Honestly, what makes you think they'll put a man on Mars in 10-20 years? They simply don't have the any track record of success to support such an aggressive time line.
Actually, that's not good enough if we're talking about preserving life beyond the probabilistic expiration date of Earth. People are talking about asteroid hits, which are once every several million year events. If a Mars colony is a hedge bet against those types of catastrophes, then the atmosphere has to last longer than the mean time between events.
The problem with that lifestyle isn't government regulation, it's population density. Estimates of the pre-columbian population of California put it somewhere around 300,000. 38 million Californians gathering acorns and shell-fish would quickly strip the land clean.