Most importantly, casting directors are looking for professional level actors.
To say that they are looking for someone talented or trained, is a given for everyone. Casting directors want actors who can walk into an audition confidently. They are looking for someone whose performance is in collaboration with the intentions of the writers. They are looking for actors who are strong, confident, and stable. Actors who give every indication that if casting moved them forward to producers, they could walk onto the set and bang out the job without needing their hands held. They’re looking for professionals.
Everyone is new at a certain point. But the right training helps you be confident even if you’re just getting started. If you’re only “trying” acting, professional casting rooms are not where you want to be!