Re: Still a bit confused
I had the same question, The only sensible explanation I've found is economies of scale: it is (or should be) more efficient to have a single main power station somewhere out of town than thousands of little internal combustion engines going around, even if they burn the same fuel. That takes into account the losses due to energy transmission over the lines.
N.B: that's not my opinion and I don't endorse nor refute it in any way. It's just a plausible explanation I read.