When you drive a Prius C do you have trouble seeing the front end/hood? Why did they put headrest on the rear seats that block your view?
Most new cars have hoods that are not viewable from the drivers seat, you just need to know its there and get the feel of the car. They do this for better aerodynamics. The head rests really don't block any view as the back window is so small.
You can remove the rear headrests for visibility when no passengers need them, and between uses store them underneath the front seats. You also could lower the rear seats fully that would expand cargo room but give visibility outside to contents of the hatch. I have dealt with both. I don't like having the visibility from outside, and I don't like to try to see around those headrests, and I find they fit well under the seats. You get used to not seeing the hood in front of you.
The rear headrests do not telescope down below the back of the seat on USA Prius C due to cost cutting. Prius C vehicles sold in other countries have the telescoping headrest design.