Scott, great find on the Erico part ... that's what was used!
Now, let's look at this thing from a design standpoint ... let's pretend we work at some place that lists these things ...
Using the 2-scew connectors as cord clamps would be OK if the thing was mounted in place; the connectors are listed for use with both SO and NM. "Portable" strips, though, have a higher strain relief requirement, and they would need to use the ones with the rubber bushings.
For the rest of this anaylsis, I'm going to assume this is intended as a 'portable' power strip.
The ability of the front plate to flex would bother me. I'd want some manner of bracing on the back of those boxes. This might be provided by using 'running thread' between the boxes.
I'd not be happy with the individula wires passing between the boxes like that. Something needs to protect the wires from abrasion. With the openings oriented as they are, I don't think they would need to be closed. I've seen plenty of 'listed' equipment that had wires run like that behind the faceplate.
There's plenty of screws there to work loose. I'd want to see some lock washers. At least they already ran the ground wire to each box.
As a 'power strip' it would be required to have a 15 amp breaker -not fuse- built into it. If it was for 'job site' use, it would also need GFI protection. I think you also need an "off" switch.
Using NM where flexible cord is needed is generally not allowed.
I know that UL has stated that receptacles are not evaluated for use with crimp-connectors (often used for stranded wire), but that's not the same as saying they aren't listed for the use. I think it's time the method be 'evaluated!' There are plenty of appliances that use crimp connectors internally, and I see no reason that using them on receptacles is any less effective.
As for the "trip and boom" fears ... IMO, the ability to securely mount something can make for a safer application. There's one less thing on the floor to stumble over. This is one point where I differ from UL. If Wiremold can do it, why can't the 'portable' strip makers?