It seems to me that everywhere I've been, the reading of Eicha on Tish'a B-av night has been broken up, with different chapters read by different people. Why is this custom so prevalent, specifically for Eicha?
I've seen Esther broken up, but not nearly as commonly, and I'm pretty sure that everywhere I've seen that (which may have been only on one place), it was simply because there wasn't a single reader who was going to be able to read the whole thing from a vowel- and cantillation-less scroll. That issue doesn't apply to congregations that read Eicha from printed books, which is the case everywhere I've been.
Similarly, for the other three Megillot, I've never seen the reading broken up.