Why does GSM allocate 200kHz data bandwidth for each mobile phone?
You've misunderstood the answer to your previous question. https://electronics.stackexchange.com/questions/166056/how-does-a-base-station-provide-multiple-channels-without-any-interference

It's not tranmitting analog voice. It's transmitting digital data. TDMA is used to share one 200kHz channel among a large number of voice calls. Each voice call is encoded with the AMR codec and ends up as about 10kbit/sec.