I'm not trying to nitpick or anything, but to my ears calling a clearance a "perk" speaks to misconceptions about the reality of working in that ecosystem. But job mobility is a real thing, so yeah that's a good point to talk about.

I can only speak from the contractor side of things, and it is true that many job openings list "must have active [clearance X]" as a requirement, which certainly keeps the candidate pool to within people already in that community. It takes 12-24 months to get some clearances, with no guarantee that after that time invested, you will actually be approved. So it is a massive gate.

But the flip side, as others pointed out, is you have large chunks of time where you cannot talk about what you did in anything approaching the detail someone who worked on a non-cleared job can. Even if you worked on some stealth mode startup's top-secret project, with NDAs and whatnot, there's nothing like the very real threat of decades in federal prison. The best way to avoid falling afoul of an unauthorized disclosure is strongly compartmentalizing your work life - this is strongly encouraged within the industry. You talk about work at work, in a vault where the only other people there are cleared. You STFU everywhere else. Easy and simple to remember. The only time this is _ever_ a problem is when you're trying to get out of the industry, where you must talk about your work experience to potential employers. That's how your perk becomes a trap.

It ropes you into that ecosystem and that ecosystem only. Most consumer/web tech companies won't understand a resume that's just "I did a thing, can't talk about it".

Tell that to employees at Lockheed, Boeing, Honeywell, Booz Allen... the list of private enterprises or people engaged in government work requiring clearance is large and varied.

They're part of that ecosystem as well. In my experience they're all miserable places to work though, LM in particular.

Have you never hired an ex-Apple employee?

Apple employees/people from other NDA obsessed firms have nothing on the cleared workers. Yea they can be cagey but their products eventually ship and they can talk about them. When you're in defense, once your project ships it stays on orbit for a decade or two.