Rear Seat Detection

If you can put a passenger detection system in the front seat for seat belts, why can't there be one for the back seat so that the driver knows before leaving the car that she has a passenger in the back?  There would have to be adjustments for the weight of a carseat, but it should be doable. 
jackie vanlieu 08/30/2014
This also was my idea. To be able to save a child from death, to me would be the greatest gift of all. Car makers have sensers for everything, So how hard would it be to place sensers in the back seat. For sure Ford would have the upper hand over other car makers.  I hope you think hard about this. Thank You for your time. Jackie Van Lieu