Hi, Maltman. Years ago, a woman bought a framed poster at a sports store and brought it to us to replace the poster with her print and mat. (Or mount, if that's what you call the flat piece of paper with the window inside.
) The frame had tape on the back, all down the length of the legs, half on the backing and half on the legs. We laid it upside down on our table, with glass face down. When my co-worker went to take off the tape, it didn't go as planned. She pulled it all off, and when the last bit released, the frame burst apart in four pieces. Never seen anything like it. Just 'wham'! There were the four legs laying all splayed out, made from this same black poly stuff, with v-nails and no glue. Great big chunks of it had broken out on all corners when it broke apart, and nothing we could do. My boss told her to have the original store replace it, but they told her, 'It's not a picture frame; it only looks like one.'
In that case, the lack of glue definitely seemed problematic, as the v-nails didn't hold at all. I suppose whoever made it would say that it wasn't a problem, though, as they held up most of the time for the reason that they were made.
Your post has me wondering whether your new framer came from a business like that one and thinks it's okay. It's possible he's been intentionally dishonest, to deflect blame, but it's also possible he thinks it's good technique. If your employers want a higher quality product and makes it clear in a positive way, hopefully he'll adjust.
You also mentioned that these are sent by courier. How long is the trip, and how are they packed and transported? If that could be improved, it will only be a plus.