Another relevant trade off is transformer size vs. efficiency. AC is used because it's very simple to step up to very high voltage for efficient long distance

Another relevant trade off is transformer size vs. efficiency. AC is used because it's very simple to step up to very high voltage for efficient long distance transmission and then back down to safer low voltages for use, while doing the same with DC requires significantly more complex electronics. However, at very low frequencies you need to use very large transformers which cost a lot and look ugly, and at higher frequencies you lose efficiency due to skin effect [1]. 50 Hz is a good compromise - transformers are of a practical size and skin depth is about 9 mm, which is larger than most conductors and therefore doesn't add much loss. If you increase the frequency to just 10 kHz (which is still considered very low) the skin depth decreases to only 0.6 mm, and you would have significant loss on even moderate sized conductors. [1] https://en.m.wikipedia.org/wiki/Skin_effect https://en.m.wikipedia.org/wiki/Skin_effect