I don't understand why humans do what they do, consistently and repetitively, against their best interests, except for money, emotions, or a lack of understanding.
Climate change has been a mainstream issue since the mid-90s. From then until now we've had massive material and ideological changes across the globe, none of which required the support or awareness of humanity or the voting public.
The internet, cell phones, social media, fracking, AI, multiple wars, changes in attitudes towards family, sexuality, and marijuana usage have all occurred during this time period. Why then has a slight, gradual reduction in greenhouse gas reduction been so hard?
Changing that cost money—and people resent having to pay more for change that they don't perceive will make much difference to their lives.
Whether they're right or wrong doesn't alter that.
Governments have been unwilling to push those changes because they are unpopular and expensive. Governments have also been unwilling to impose hardship on their people if other countries aren't going to do anything. A lot of people, in this thread, don't think it will be bad, or that it will happen after they are dead.
In terms of making a plan, what is the point of making detailed plan if nobody is going to follow it? Also, there are lots of things that we don't know how to do yet, and can only plan to investigate.