Earlier quoted context omitted.
> so the only reason to do it in house is they can't trust any company they hire Now I'm deeply confused. Any company hired either has a profit margin (plus enough to fund an "Oh shit" fund in case times turn bad) or will not stick around longer than a few years. At which case why not just hire people directly and cut out the other company's profit margin? Assuming you hire similar people at the same rate, using your…
Doesn't this logic apply to pretty much everything? Why hire external anything then? Why not do your own deliveries, hire your own trucks to transport goods etc? There is a cost to taking on things that aren't part of your core business too.
Similarly, Google doesn't ship enough stuff worldwide to justify drivers, insurance, trucks, jets, etc. - Fedex has the size and scale to make every package a couple cents cheaper, so it's just not worth it for Google.
The only other argument I can think of is the challenge of keeping every plate spinning, in good times and in bad. This is where your point of having a cost to take on something outside your core business comes in, but we seem to be in an era of mega-corporations - I'd expect lots of companies to snake tendrils into whatever will save them a fraction of a cent every time they have to do something.