That's not what anyone means by modification. Of course you can choose a custom factory setup (which is purchasing a new car without modifying it) and swap an official part for another official part (usually called maintenance). This has nothing to do with what people usually mean by car modification, where you are absolutely free to change whatever you want, and do crazy stuff the manufacturer never imagined. They don't allow true modification by the normal meaning of the word for anyone who is interested in cars. They only allow you to choose from a limited selection of factory specs. And as you mentioned the options are minor, not the drivetrain itself. No real car enthusiast calls that modification.

Search for "3000hp lambo" on youtube and you'll see what modification actually means.