"Whoops I made $600 from something that cost me $10"
I've written about this here some time ago - you don't pay for the soap dispenser or trash bin itself, you pay for the paperwork showing that it is safe to install this trash bin, soap dispenser or whatnot into this specific model of aircraft or spacecraft, and you pay for the paperwork that details the entire life of every tiny little piece used to manufacture that component. For flight-critical parts, IIRC that goes as far as to documenting the specific lot of the iron ore that was used to make the metal sheets, so in the event of something cropping up where something got fucked up in the mine or the smelter, you can recall every single part that could be affected. And there's lots of testing (and associated waste) at each part of the step.
Anything that goes into an airplane or spacecraft has ridiculous rules attached to it... rules that were literally written in blood. Aerospace is amongst the safest ways of transportation because of decades of crashes and learning from each and every single one.
Your average Home Depot soap dispenser has none of that, if it breaks it breaks.
Surely there's a more cost-effective happy medium somewhere between "just buy the Home Depot 2-for-1 special" and "we ran a background check on the guy who mined the metal"
The very second you start making an exception because "a soap dispenser is trivial", other stuff will get labeled as exempt (or treated as such), eventually there will be no one knowing what is exempt and what is not, and someone will treat something as exempt that clearly shouldn't have been exempt, causing an incident.
In aircraft and spacecraft design and manufacture, the rule is "safety by design". Treating everything as "needs to be certified by default" is fail-safe, it eliminates entire classes of incident causes.
As we've seen from the slight "windows falling off planes mid flight" problem which they furiously tried to cover up, Boeing has a bit of a problem with making exceptions where it actually matters.
A far more likely explanation here isn't that Boeing is being too strict and disciplined over all things up to and including a soap dispenser, but that a bunch of people have their noses in the trough and have figured out a hack to drain money out of the federal government budget.