I have sympathy for more complicated cases, but they're the 20% approaching 0.01%. They necessarily can't be used to justify the 80% case which is as the GP described.
If the 80% have picked low cost optometrists (such as those attached to big chain stores or glasses retailers), then you get what you pay for. My optometrist offers the same to anyone who uses her, and has for decades. The office specializes in optometry; and their waiting list for appointments is around 11 months long.
You miss the point. Those 80% didn't just choose low cost optometrists. They don't need high-end optometrists. A specialist with all the qualifications to help the issues with your eyes is far and above what I need to fix the relatively minor flaws in mine.