Difference between listed and unlisted companies recommended actions

Hey,

I was reading the article “EXAM TECHNIQUE FOR ADVANCED AUDIT AND ASSURANCE-Ethics” and for the answer to a scenario given, this is what they’ve commented:

“In other circumstances, the safeguard of using separate teams to overcome self-review threats or considering the competence of the firm to provide this service would attain credit; however, in this case, the client is listed so these points are irrelevant here.”

Would you please explain why these two points are irrelevant because the client is listed?

Thanks a ton!I really appreciate what you guys do .