Brake Noise or Squeaking brakes can be annoying. Sometimes the thickness of the pad is not the issue. In this case, the brakes had been squeaking for over 5 years (I know because it was my vehicle). I knew the pad had plenty of thickness. The brake noise was coming from the pad material. It was a heavy-duty pad that made noise but lasted longer and was able to stop big vehicles better.
So, being a mechanic. I lived with the noise. This story started when I bought the vehicle. It made a noise from the day I bought it. The dealer had put on heavy-duty pads.
So moral of the story, the brake squeak on your new (used) vehicle could be the type of pad on your car. But to be sure, have your brakes checked to make sure.