The real problem is powering them. Batteries have a terrible energy density compared to hydrocarbon fuels and charge slowly, fuel cells don't seem to take off, and using an internal combustion engine to power an electric engine doesn't really solve anything. In fact, the simple fact that powering an electric engine with an ICE may be a good idea speak volume about both the superiority of electric engines and the difficulty of powering them.
So yes, the electric motor's dominance is inevitable, but we are not there yet. Battery technology is just starting to become viable, but electric cars are still heavy and expensive, have limited range and we don't really have a good, universal charging infrastructure yet. It is not because of "the best efforts of politicians", it is because it is technology that is just starting to become viable.