As a field service guy, many "standards" are not standard unless carved in stone.
Example, company I worked for, certain things (usually power) were consistent. So power was good, data was "wishy washy".
Certain FTDI adaptors worked, others didn't. We used a lot of boards from Rabbit that did what we needed, others didn't work.....
Sorta same spec, but different....
"It's the exact same thing, only different....".
Sigh.