I'm thinking about this selfishly. I'd have to go and take a test. But my employer would probably pay for it. Maybe if I wasn't already employed, it'd be on my own dime, but even that isn't too unlike the school I've already paid for. And I'm sure I'd pass the test. As long as I don't have to recertify too frequently, it probably wouldn't be awful. And also selfishly, if it keeps some riffraft out, I wouldn't hate that either.
I guess my biggest concern, with parallels to that time I sold life insurance, is that they test for one thing and then in practice you do a different thing. I hear the same is true for realtors. So.. it becomes an exercise in memorizing some BS that you won't use again after the test. If we do this, the software engineering test would need to be updated at least annually, and better be written by some well respected security researchers.