The problem with having the government step in is that well, the vast majority of the population would disagree with any attempts to limit consumerism/things that may damage the environment, and any politician who tried them would be a political pariah.
I mean, imagine a government actually trying to limit how often people/companies could fly/run planes, how much meat they're allowed to have, what kinds of cars were allowed, etc.
The immediate reaction would basically be:
A: Most of the population flat out ignoring them and their attempted guidelines, leading to bad press if they tried to enforce them.
B: The opposition having a golden opportunity to win over the current ruling party's supporters with claims they'll revert said changes after the next election.
C: Said main party's polling support crashing straight through the floor as most of their supporters abandon them.
D: Tons of bad press in general, especially if certain people/companies seem to be 'getting away with' behaviour they don't allow the rest of the population to indulge in. You can already see this (for good reason) with complaints about stuff like Davos and how all these politicians and actors/celebrities are taking private planes everywhere.
E: Their own party members jumping ship, especially if it's a larger/established party which went all eco intense.
F: If things got bad enough, outright civil war/revolution/military coup/riots/etc. And given the percentage of people who'd back such restrictions/law changes is so tiny, it probably wouldn't end in their favour.
The government stepping in would (if done as strictly as some articles/guidelines suggest), lead to a lot of civil instability and any political party implementing it basically collapsing.
So the options are basically either 'hope everyone becomes more environmentally conscious (unlikely)', 'get the government to step in' (unlikely, may lead to wars and revolutions, would sink their reputation), 'hope some sort of invention makes carbon capture much easier/resource efficient or makes clean energy super cheap'.