Thats because they are federal officials. If they have clearance of course the government trusts them, the government knows every little detail about their life.
You may be confusing "they have every little detail about their life" with the more generic and less useful "they have a lot of arbitrary data about their life".
If there is something a government is good at, it's making you fill in endless forms of data that is neither conclusive, neither guaranteed verified, and in the end rarely useful.
If the government could easily know every little detail of the life of government officials, it'd be quite hard to explain the constant stream of corruption schemes discovered around the country, often randomly, accidentally, and years after the fact.
Until recently, pilots of airplanes themselves had to be scanned every time before flight. You'd think if you trust someone to operate what's basically a giant winged bomb full of people, you might as well trust him not wear a bomb in his pants.
What you see is rather a simple after-effect of basic human psychology and lack of public control. Left to their own devices, lawmakers see the world as any human would: me, us, and them. Me is me, I trust myself. Us are my colleagues and the people who fund my campaigns. Them is everyone else.
As it goes, inconveniencing "us" is a big problem as we have serious work to do, which we know in detail and we discuss in corridors every day. That's ok, because we know each other and you can trust "us".
While "them", a quick scan and grope shouldn't really harm "them" much, especially considering you can't trust "them".