It's always real people. The reason they are allowed to spam you is because it is considered the "freedom of speech" of the person sending the text. The opening text however is a prewritten form text that the person just spam clicked send on. Any additional back and forth will be with a person who will try to follow a script but sometimes will engage with you if your questions don't fit closely enough to their stock replies. If you come off too hostile or uninterested though they will just remove you from the list.