Green in not the only reason
Electric trains are much nicer to travel on than diesel. They're quieter, accelerate better. They're also cheaper to maintain. Same is true of cars. The infernal combustion engine is noisy, smelly and requires high maintenance.
It's a shame batteries aren't up to snuff yet. However, got to start somewhere.
Also central electricity generation is greener and more efficient than lots of internal combustion engines and and has potential to improve. There's two new nuclear technologies on the way: TWR and thorium neither of which suffer so much from the bugbears of uranium fission.