Most drives are not capable of reporting C1 errors when performing a Disc Quality scan, and your drive is obviously among them.
It would be theoretically possible to get a scan with zero C1 errors, just like it would be possible to win the lottery every week for a lifetime. The probability is probably the same, i.e. for all intents and purposes impossible!
Many drives can report C2 errors in a Disc Quality scan, but they don't all agree on what a C2 error is. Discs burned with good quality should have zero C2 errors, so from your scan it's impossible to say whether your disc has zero C2 errors or whether your drive cannot report C2 errors.
If you want to know this, you can take a CD-ROM or CD-R that you don't need for any other purpose, and use a pen with permanent ink to create a thin radial line going from the outer edge and part of the way across the disc surface towards the centre of the disc.
Once the line is dry you can scan the CD, and if your Disc Quality scan doesn't show any C2 errors, then your drive is not capable of reporting them.