Sparky, you may have confused "safety" with "quality." Just as a Mercedes has to pass the same DOT standards as a Yugo, no one ever considered them to be of similar quality!
UL, CSA, etc. tests are done under lab conditions with new products; there is little attempt to simulate actual wear & tear, abuse, or the enormous range of conditions. Some subjects aren't even discussed, nor are there industry standards.
(For example, there is a specialised market for "high-abuse" or "vandal-resistant" fixtures, but there are neither tests nor standards).
Personally, I find the $10 "spec" grade devices to be more than is necessary; there is usually a remodel long before the device tires. At the other extreme, the $1 POS units often break during installation! So, for me, the choice is usually a "commercial" grade with screw-clamp back wiring.
