Any HD channel decoder which is with any Cable or DTH operator has options to show the demodulated standard definition version of HD channel in either 16:9 or4:3 aspect ration, its upto the operator in which format he or she wants to telecast the demodulated feed of HD channel. Normally as Standard Definition version is for Normal TV users , most DTH opr Cable ops telecast the downscaled feed in 4:3 aspect ratio.
Regarding standard definition chennels like Zee Cafe or Zee Studio being telecasted in 16:9 aspect ration, that is being done by the concerned broadcaster, in this case its Zee so a DTH or Cable operator can't do anything.
I hope this helps u all clear the doubts