So improve them to make them reliable. The first version of new technology is rarely robust. How good was your cell phone 15 years ago vs. what you can get today for 1/2 the price? Did we abandon the cell phone because analog dropped calls and had poor sound quality? I'm sure Model T's broke down all the time, but we still drive cars - 100,000s of miles now.

I'm also guessing that TSA incompetence never looked at the maintainability of the machines. I can't believe they can't be cleaned and have to be discarded because of "dirty air in airports". How about employing a maintenance technician in place of five TSOs doing pat downs to make sure the machines are up and running, filters cleaned, or whatever needs to be done. More than likely TSA said "That's too hard" and "Ohh! Shiny new backscatter machine - lets go play with that!" instead of trying to really develop the technology.