My thinking is companies and people will take the path of least resistance. In this case it is sticking to gas powered engines. Maybe we need states to start implementing these laws to force companies to start investing more in R&D in order for this to happen quicker? Maybe moving from horses to vehicles was such a huge improvement that people were willing to do it. Moving from a gas powered vehicle to electric or any other zero emission system might not be seen as a big improvement and therefore the willingness is much less.