A few years back I worked in a factory that was serious about lockout tagout Zero Energy State stuff. That was fairly new 20 years ago, not everybody enforced it to the extent of firing employees for the first violation.

But what we found was that the standard disconnects where you pull a lever did not stand up to constant switching as we did machine adjustments. And they sometimes failed catastrophically, and we had a few injuries.

Using copper pipe like that makes me cringe a bit but it's possibly safer than pulling a lever.

Quick veer off topic: working on my shed this weekend I had to move an outlet to replace a stud. I pulled the disconnect lever on the main subpanel. Put a meter on the outlet, it's still live. Really? Lights are out, nothing works, but that outlet was hot. So I pulled the fuse block out, looks exactly like that piece in the OPs photo, now the circuit was dead. Just goes to show, always check.