Not worth the effort even thinking about it, much less going through the trouble of trying to strip it off. Which may be likely to cause troubles for the host plant anyway. Lichen is completely harmless to whatever host it might be growing on - rocks, fences, cars (yes, I have had lichen growing on my ungaraged car roof) and trees and shrubs. I could show you entire lichen forests in my area but they are really only very visible in winter when the trees are leafless.

Rainfall is not a significant factor in their formation. There are lichen that grow in deserts.

Normal to have lichen on your trees here in Georgia. They don’t cause problems no need to remove

That's good to know, appearances can be deceptive even if it does look like a parasite sucking the life out of whatever it's grows upon. In the past it's only been spotty on some of the crept myrtles but now it's much more prevalent.