That's just a fundamental misunderstanding of what the clearances mean.
First and foremost, they're just a background check. There are lots of janitors and painters that have Secret or Top Secret clearances so they can work in buildings that contain that kind of information. There are large swaths of people that work in factories with clearances that really couldn't tell you anything of value - but they have to pass a background check to get the job.
Then once you narrow it down to the people that have actual classified knowledge, they generally only know a sliver of a small area and that's it. "Need to know" matters a whole lot.
The people with wide ranging access to lots of different databases is very small. I would bet Bradley Manning is one of less than 50,000 or so people with that kind of access.
There's a difference between secret from US citizens and restricted from public (I.e. worldwide) disclosure.
Classified material is kept from US citizens as a side-effect of it not being public. Believe it or not there are certain limited exceptions in practice to those classification requirements, since the exceptions don't translate to full public disclosure. E.g. a military spouse knowing the week to expect their spouse's return home, something which is normally classified from public disclosure until after it's already occurred.
That's a ridiculous mockery of anything they think should be a "secret" from US citizens.