Do a check with them and make sure they mean *all* trees - I would bet this is stuff like shade trees that get really tall and might impede the neighbor's views and so forth.

Also, I suspect that if you had a master plan and you showed it to them, they'd be waaaaaaay more likely to be reasonable. Lots of folks just stick stuff in the ground willy nilly and it dies and looks ugly. (Our redbud looks ugly right now because being transplanted in may did NOT agree with it and it has no leaves. But we know it's wick and we're taking careful care of it so it should be *gorgeous* next spring....)