About a decade ago I worked for a communications company, a few thoughts relevant to this thread:
1. The vast majority of our fiber did run underground. The only aboveground was where it would run along high tension lines, not normal point of service telephone poles. The stuff you see along a "telephone pole" is for end users and no one cares about that, no one will go and trim those, since it's not worth the cost. Perhaps the "last mile" to a big customer might go along these, but I never saw that.
2. Yes, the trees would be better cut (that was part of my job). If multiple utilities share an easement nothing stops a second from going though. I suppose it depends on the local laws and the easement restrictions, but we were scorched earth whereas the electric company seems to be minimally invasive.
3. I didn't work for a cable tv or a phone company. I'm talking providing networking to ISP's, universities, broadcast stations via a multiple connector cable. I'm not sure what you saw being repaired, now that Google Fiber and FIOS exists maybe they need a fiber repair for a line that doesn't get the attention ours did.