It looks like the Washington authorities forgot to give some basic education to voters about the concept of carbon price as a strategy for climate-change mitigation when they adopted the new carbon-pricing program. It is all so simple to explain. Wikipedia as usual does a good job in its carbon tax article.
That might deny unwarranted success to the usual climate-deniers that are behind the petition to repeal it.
In a nutshell: Yes, carbon pricing has the effect of making gasoline more expensive. And that is exactly what is needed. Because the alternative, doing nothing, is in fact more expensive.
The problem is that in the current situation carbon emissions cause a so-called “externality.” That is a true “hidden tax” that we all currently pay willy-nilly. The carbon-price system is aimed at shifting the burden of that hidden tax to the people that cause it. What could be more equitable?