Maybe she has less ventilation, it's certainly an issue most don't understand. Continuous venting goes a long way, as does good soffit vents to get the fresh air from the eves. On most roofs I make sure there is less than 16' from the end of the eve to the ridge/vent, if more I add pod vents. I also like at least 2" of opening total at the ridge, more if possible, but that depends on the vent being used and whether you have trusses, or a ridge board/boards which reduce the amount of the opening and the coverage of the vent.When I redid the roof about 28-29 years ago the tree (the 4 tree clump) were not terribly big. They were far enough from the house that catkins and burrs never landed on the roof and there were certainly no overhanging branches or even shade. The moss and lichen issues started maybe 3-4 years ago. I am due for a tear off reroofing in the next 3-5 years and a continuous roof vent and zinc strips are in those plans. I redid one of my back neighbor's roofs around the same time (also added sky lights, repaired a broken rafter, etc.). She had moss and lichen problems so I put zinc strips on her roof and it helped. She had picked out a different brand and style of shingle and they didn't hold up as well as mine... She reroofed last year and I did not see any zinc strips added so she may have a problem again on the north side of the gable roof.
I do happen to have one of those interpreters....
Zink strips work great, many of the newer shingles have anti fungal properties(read chemicals) to help stop growth/blackening of the roof. Newer shingles are also rated higher than in the past, looking at the actual weight per square is a helpful indicator of quality.
If you use the interpreter, they may just start actually speaking english lol. That being said, you can always tell anyone who asks that you thought they could help you tear it down for cleaning, you weren't threatening/brandishing, unless it's not a Chinese model . Too bad those can't be bought for the prices like they used to get for them at the shows back in the day(that was about 75 for my day). The last one I bought was 125 iirc.