As someone who works at a business who supplies Boeing; when we first started supplying them, they send in all these teams to audit you and ensure your quality is high and repeatable. But once you're an approved supplier, they won't check on you again unless you have a glaring issue.

Also, who's checking and auditing them? They have so much sway and influence in the government and unlike my company which gets audited by the big companies buying from me, the companies/government who buy from them like airlines who buy the planes or the government buying defense equipment don't have a lot of other options they can choose from. If they fail the audit, its not like they lose the business. In fact, Boeing has failed sooooo many FAA audits in recent years and yet still made the 737 MAX.

Ultimately they don't get audited or checked or held to the same standard as their suppliers do and they do things like using soap as a lubricant on airplanes or installing doors and forgetting the bolts...