"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.
Depends on the failure mode. Assume the screws with which the soap dispenser is installed are spec'd to wrong torque and the installation causes stress fractures as a result that end up propagating through the aircraft...
Yes it sounds far-fetched, but aircrafts have crashed due to microfractures caused by improper torques on other components...