According to my dad all cats are girls and all dogs are boys. That’s just the way it is. Every cat is a ‘she’ and every dog is a ‘he’. Of course for many years we had a male cat and a female dog, but that didn’t matter. My dad doesn’t seem to be alone in this sentiment. My father-in-law also always refers to dogs in the masculine and cats in the feminine.
Something similar happens at this time of the year. As people start searching for their christmas trees, often they refer to every christmas-tree shaped object in the lot and in the woods as a pine tree. Just like all cats are not girls and all dogs are not boys, all evergreens are not pine trees.