This is an incorrect generalisation.
Only LiteOn Mediatek chipset based DVD-ROM drives have been shown to be unreliable in any way for PIE/PIF scanning, due to their inconsistency.
However, AOpen 1648/AAP has been very consistent.
The only reason the scans are different, is because they are different drives.
An equally valid question to the original poster would be: "Is my BenQ 1620 useless for scanning, because it differs so much from my AOpen DVD-1648/AAP?". Neither one is "wrong". They just read differently. The same applies for Toshiba SD-M1802, Plextor 712/716, LiteOn DVDRW burners, Optorite burners, etc.
I'm beginning to think that Erik Deppe should include a compulsory introductory test to CD DVD speed which would explain all this.
We would have a thousand posts less per month here at CD Freaks
PS To re-iterate: there is no single drive on the consumer market that is "the best" or "only correct" or "most accurate" for dvd PIE/PIF/POF/jitter/beta scanning. All drives just report how they are themselves able to read a particular disc. They do not report errors directly on the disc.