Which are historically the hardest problems for engineering orgs to ship: precisely because they cut across team/org boundaries.

Suddenly the Maps team need to give a shit about the Calendar team, etc.

And both teams tend to exaggerate and say 'Sure, our side of the integration is finished... it must be a problem on their side.'

Ironically, Amazon-as-a-company probably has the most experience retooling this way -- from the Bezos API memo. Because that's what it will take.