Airbus ( and I'm sure pretty much all the other manufacturers ) has all the processes for training the workers about this problem, how to avoid it, how to deal with it when happens, check-in and checkout all the tools at the start and the end of the task, inspections, etc. this is so basic it hurts.
If the protocol says "(1) Check out tools before using them. (2) Check in tools when returning them. (3) Verify all tools checked out have been checked in before marking the job complete." that's one thing. Sending employees to training on how to do this and seeing daily clipboards by the tool room with initials might make you think the protocol is in use. And if there are supervisors making sure that the clipboard is full of initials at the end of the day, that can give you a nice warm fuzzy feeling.
The problem comes when supervisors want to 'look good' by having no deviations from the protocol. If people are post-dating their check-in or pre-dating their check-out, or checking stuff in that's still in use by a coworker, the protocol is less than useless.
When humans are tasked with following those protocols, they'll make human mistakes sometimes. If there are no mistakes that's not good, that's bad - it indicates the metrics are being fudged. I think any supervisor that fails to find a deviation from the protocol or who can't list an event when the protocol required action outside the norm does not look good.
Similar stuff applies to software development: If you're doing code reviews, or testing before check-in, or signing off on releases, and can't point to a time when the protocol said "nope, go back to the drawing board" you're not actually making your development safer you're making it a hassle.
It also might be downstream or upstream of the Boeing factories, like at one of the companies that manufactures major components (example: Spirit AeroSystems manufactures the 737 main fuselage and I'm told Section 41/cockpit of many aircraft) or at one of the maintenance facilities.
That same guy also said it had to do with the location of that new factory and the lack of company culture paired with managers who just had the numbers in mind.
<Interruption>
<Return to work>
You start out three step before your last step.
You repeat/check those steps.
Its time intensive as hell, which is why the usual interruption to egostroke for meddle management does rarely happen in aircraft maintenance and production.
The most WTF moment for me was when he told about a whole ladder that has been forgotten inside.
I would guess the NC plant was commissioned without much, if any involvement from the Seattle people, if there culture was that radically different.
It’s also why Boeing has been cutting their key engineering staff in Seattle — they also unionized. In fact, rumor has it that the entire reason MCAS/737MAX debacle happened was outsourcing and contracting shenanigans to break the engineering union.
It turns out moving senior management away from the rest of the company and getting in an ugly fight with your talent before petulantly building a non-union plant elsewhere leads to low quality products and out of touch executives.
Who could have known?
Oh yeah, my friend’s uncle who flatly said when his generation of engineers retired, Boeing would lose the ability to make planes.
And everyone else.
The other story I remember was he found that defective parts, which had their own area so as to be separate from good parts, so they wouldn't be used, were going missing. When he confronted a manager they told him to not worry about it. The parts were clearly going into planes so they could ship them out.
He was asked at the end of the episode if he'd ever allow himself to fly on one of the planes that went out of the factory he worked in and IIRC his reply was an emphatic "no".