Quality aside, art still has copyright for these exact reasons (and photographs are no different, long settled case law). So you can't just say "well no one cares about this blurry dog photo". Courts need more precise language than "care".
If it needs millions of photos of dogs and trees you
1. Take them you self
2. Pay someone with a db of dog and tree photos soem agreed upon amount (Aka someone did the work for you already and you value their work)
3. You scrape only on photos you are sure are CC0 or any other kind of permissive license. I'm sure you can find a few million dog photos this way.
But clearly they value #2 without payment so lawsuits were inevitable. Maybe because #3 took too much time and they decide #2 is worth the legal fees to be first to the race (something else I'd want fixed, but that's another rabbit hole).