That’s good then. Although I hope they also considered what happens if there’s two of them on a circuit, because if the mains power goes off, but there’s another panel on the same circuit, they’d each see the other’s voltage on the line, right?
And yeah, you should verify that a circuit is de-energized after you flip the breaker, but I’ve seen both some real weird electrical work, and some electricians who aren’t that careful.