Dsg not cvt. Both are different

drum is there to reduce cost and reduce the need of applying abs feature on the drums as drum brakes rarely lock up at high speeds

Nah.. its more or less the same. Drum Shoe or Brake caliper pads change. Drum shoe would have problem working under intensive & prolong braking as the design does not have proper ventilation. Solid disc are much exposed to the atmosphere hence when you're car is in motion, it will cool the rotor disc. To reduce the braking power to avoid lock ups, you will notice some rear disc brakes are smaller than the front ones.