These cars being /performance/ oriented might be a hint. For a car to go fast it needs air, like a lot of air, air that engine needs to dispose of quickly in order to get a fresh batch, and adding complex muffler systems limits how much airflow you can have.

Add to that ecological requirements and you have a very tight margin that car manufacturer can tweak in.

Also just because car can sound loud when driven in full throttle, doesn't mean it has to. It is on the driver if he chooses to be a nuisance, not manufacturer(Straight piping an old beater car is dirt cheap, having a hole in exhaust is even 'cheaper' and is much louder than any of the expensive, performance oriented cars in question.