"Internal conformance testing" just what is this exactly? The Honour System.
"The Honor System." works if you have honor.
As it is now, I have much more trust in honor of a good Japanese company, than in USA safety certification agencies..
But that is just feelings.
Facts are, I know many companies that do internal testing, and do it well. Some products are hard to make compliant, and any precompliance must be done in full blown in house compliance lab during course of design. Once you have full lab, you might as well use it. They go independent party only if mandated. And since nobody wants liability and competition would gladly crucify them, they do not only good job but make sure there is healthy reserve if possible...
Fluke does exactly that, and so do many others. OTOH, FLUKE does a lot of work with industries that have mandates for specific testing, so they go outside for those..
A good question would be: is there any verified information how many industrial accidents were caused by using UNI-T meters..?
A research, by numbers, how much more accidents happen by using UNI-T than Fluke?
I would like to see that information..
I still have UNI-T UT71C somewhere. Worst part is that it worked very good as a electronics meter at desk, it was accurate up to specs for years, had very fast peak detect mode, and centered bar-graph mode, very accurate AC mV/V measurements with better than 100kHz bandwidth, high Z mV DC mode, etc. etc..
It never got damaged. I didn't try to give it "Joe treatment" though, but in a controlled lab environment (with basic static control) it survived.
What was wrong with it was mechanically really cheap. Input jacks are some leftover pieces of sheet metal that look like someone bent them by hand, inserted into inner part of plastic socket. That makes it that thin plastic inner tube is holding all the inserted banana forces and they break in no time (and it wasn't fancy glass filled good plastic, but some cheap plastic). Meter was few months old when it started cracking. I had to find some thin brass tubes and remade those sockets, inserting tubes into plastic and fixing it with epoxy. It was solid since.
It is like Joe said for UT181: it had all the potential to be great meter, they did many things right and then screwed up on a bit of PCB layout, one resistor (mine is EU version with MOVs and big fuses), plating on a switch and better input sockets..
And for crying out loud, on UT181, use standard Li-ion cells (like 18650 or whatnot), that can be replaced by user so you can also charge them outside..