It is a very nice question. You use subjunctive because yo don't actually day that always people don't respect animals. The correct meaning of that statement is: In my opinion, it's a shame when (onlu when it happens!) people don't respect animals. If you wrote "respeta" the meaning os: it's a dhame because always people don't respect animals. So the sense changes.

1.) Me parece que es una vergüenza que la gente no respete a los animales. You use subjuntive because it is a valuation (es una vergüenza) You have to make a difference between what you say or think (opinion), and the valuation. For instance: - Me parece que la gente no respeta a los animales ---> opinión en indicativo - Es una vergüenza que la gente no respete a los animales ---> valoración en subjuntivo 2.) Me parece que es una verdad que la gente no (indicative or subjunctive here???) a los animales. This phrase does not sound natural to me, I would rather say "Me parece un hecho que la gente no respeta a los animales". You can only use indicative because you are expressing your opinion without making a valuation Hope it helps!

you can actually use both but it sounds more natural to say respeta