It's also worth noting that these ZBV's deliver a higher radiation dose per scan than an airport scan. That's still quite small, especially compared to a medical X-Ray, but radiation exposure is cumulative. Effectively, every time one of these vans drives by you it's as if the government is giving you a lottery ticket where the prize is cancer. The odds of you being a "winner" are astronomically small, but should the government be able to hand you these lottery tickets without any cause for suspicion at all?

I also suspect that, like airport scanners, these scans amount to nothing more than security theater and pork-barreling for contractors with government ins.