You can’t get an up front price because of insurance, not because it can’t be provided.

You can't get an up-front price even if you're paying cash. Maybe from an independent dental practice, if you annoy them enough, or other practices that are standalone.

That's all because of insurance.

If they give you pricing that in any way contradicts what they tell the any of the insurance companies they are charging, then the practice can get themselves in hot water with the insurance company.