Most of the vehicles in that class do not offer heated/cooled rear seats even as an option. Only few flagship vehicles offer that as a standard feature ( Mercedes S class, BMW 7 series). The RDX leads the class by offering heated/cooled front seats as standard. Lexus RX has that as an option. Maybe you can get it as an option on a bigger, more expensive MDX.
DJ X thanks for your response. I wasn't worried about radiant seat heat so much as warm or air conditioned air outlets for the back seat passengers. Sorry to mislead. Anyone sitting in the back of our RDX is without air circulation. That seemed a little spartan, even for an "entry level" luxury crossover.