Both BMW and Mercedes have models comparable to the Model 3 financially. I'm sure a 2-series or 3-series BMW, or CLA or C Class Mercedes far surpasses Tesla's build quality.
they cost the same, but are they electric? otherwise, it is not apples to apples.
To be fair, in this case it is apples to apples. The average car consumer does not weigh in the electric component with so much weight to overlook poor interior quality. Tesla's cars must be on the same level if they are to win the public's heart.
Why does it matter? The customer of this segment doesn't really care about the engine.
Of course they are. I don't care if the car I drive is electric, gasoline, diesel, biofuel, or hydrogen fuel cells. The majority of vehicle purchasers are the same. If you're in the market for a high end electric vehicle, your choices are a Tesla, an i8, and I think that's about it.