They're standard construction screws and they're screwed into tin.. it's a ridge vent, there's nothing but air under that.
Edit: thoughts...
Screws are not structural. They are not permitted in anything load bearing. They have no sheer strength. My permanent tie off is still on my roof (so I can't read it right now), but I believe it's supposed to have #10 hanger nails. And every hole has to be used. And they all have to seat in wood. It's strength comes from the triangular shape and the sheer strength of the nails.
The fall arrest strap wouldn't even extend before you hit the ground with the way those are fastened. On a 7/12 pitch... Terrifying...
On the tin roof with a tin ridge vent, you'd have to use a single leaf anchor, not the dual leaf like pictured, and has to be fastened into the truss wood **on the opposite slope of where you're working**, then has to be moved or another added when the worker switches slopes.