Yeah, I think if a black guy sits down in a whites-only restaurant, the white people there should be allowed to lynch the guy. That should be enough of a deterrent to stop those people from breaking the law.
Clear how stupid your argument is, now?
There are a tonne of methods to enact political chabge and one of them most definitely isnt stopping traffic.
Unfortunately, it turns out the ones that actually work usually involves pissing people off enough to care. That requires being pissed off enough yourself to willingly break the law, knowingly accepting the consequences for doing so.
The UK has actually already passed a carbon tax and is already hitting targets that have been set. So I'm actually surprised this group chose to begin there. Probably time for a little more dramatic action elsewhere, though.