Actually, companies compare their cars to Toyota because many people (like you) THINK Toyota is better than other makes. Provide evidence that such a notion is not exactly accurate, and you could sway people.
Just because a product is more popular than another, does not make that product better.
Marketing comes down to anticipating and influencing consumer's behavior. The Toyota comparisons adds are a perfect example of good marketing: "You like the Camry because of this? Guess, what.. This car (X) does that better."