Although (A) establishes that people usually don’t actually compare prices, this doesn’t establish that people don’t have the ABILITY to compare prices charged to what the repairs are worth. They might be ABLE to, even if they tend not to.

(B) establishes that the auto repair industry does not meet what’s required to be a properly functioning free market. If some people can’t determine what the repairs are worth, then they can’t compare prices to what the repairs are worth. So it’s not true that “each” potential buyer can compare prices to what the repairs are worth.

(C) establishes that some auto repair shops don’t give written estimates. This doesn’t establish that buyers can’t compare the prices charged to what the repairs are worth. Maybe people get verbal price estimates in person or over the phone. Or maybe they can still get price estimates from a large number of sellers, even if it’s not all sellers.

We care about whether people can compare prices charged to what the repairs are worth. Whether the prices are higher or lower than the repairs’ worth is a separate, irrelevant issue.

(E) doesn’t establish that people can’t compare prices charged to what the repairs are worth. Even if repairs don’t have a standardized price, the repairs can still have a worth to the potential buyer. The potential buyer can still compare prices charged to that worth.