Which is why tree trimming easements need to be quite a bit wider than the road right of way. The trees need to be cut back so that when the leaners fall (or are cut), they miss the transmission lines.
The brown tops may be the result of the conductors swining or sagging near enough to the tree tops to flash over. The result is a circuit trip and reclose, IOW, the 'bumps' that my neighborhood is famous for. :-(
These are a sign that the circuit is in desperate need of tree maintenance. Sadly, the circuit voltage you are referring to usually doesn't fall under the jurisdiction of NERC reliability guidelines since they don't 'interconnect' utilities.
Because the phone circuits still work with a tree leaning on them, unlike overhead power lines. The trees do damage to the telephone cables (breaking the outer jacket and allowing water in) and need to be removed eventually.