There is a huge difference between engaging in dangerously predicable behavior, and having consistent standards which treat the public with dignity and respect.

Let's look at one example of TSA's supposed "unpredictability" model - whole body imaging.

WBI scanners are installed at most c/ps through out the US. Which c/ps have them and which don't is a known quantity - there's a list right here on FT. But they're not in operation 24/7; when approaching a c/p equipped with WBI, you don't always know whether you're going to be selected to go through it or not. Sometimes, you go through the WTMD, sometimes you go through the WBI. And sometimes, even after you go through one of the scanners, you get a full-body rubdown with genital contact (laughably called a "pat-down" by TSA). Which one of these screening methods you get is unpredictable, which has multiple negative consequences for passengers.

But the unpredictability is absolutely useless as a genuine security measure, because there are only three possibilities, and all you have to do is be prepared for any or all of the three - WTMD, WBI, "pat-down". Prepare for those three methods, and you're home free.

Frankly, all passenger screening, predictable or not, is nearly meaningless because most cargo is still not screened, nor are airport employees, vendors, and vendor supplies which enter the sterile area by means other than the c/p.

And that's just an example of intentional unpredictability. The unintentional unpredictability that we complain about constantly comes from items that are supposed to be consistent from c/p to c/p, such as which IDs are acceptable, and whether the liquid limit is 3oz or 3.4oz. These examples are not security measures, they're simply examples of crappy training, lax standards, and a complete lack of accountability in the organization from top to bottom.

So, that's why we're complaining.