I suppose that there are some very weird "acceptable" practices used specifically in mobile home construction. They're essentially in the RV category, as far as manufacturing goes. In comparison to real home construction practices and materials, many of them are basically the equivalent of the China/India version of machines and tools. The ones I've worked in can cause ya to feel sympathetic for the owner.
The plumbing is sub-standard to normal home construction.. I've also seen fixtures that are actually marked/designated/approved for RV (on the back or bottom, where it's not easily seen).
I've never seen one burn, but the bare frames are shown on the news frequently.
The screw/captured wire termination is a reliable connection for current, and most better quality replacement cord ends (stranded wire) use these types of terminals.
The only advantage I see for IDC electrical power connections is speed in the assembly process. The romex skin is peeled off for about 5", then the IDC device is pressed shut on the wires, where I saw them used. Feed through and branch end connections require no cutting, stripping, twisting, pigtails or fastening. Total crap in my opinion.
WB ................