We live in a world where Air Force Generals join boards of air plane manufacturers, so a quiet understanding between suppliers and buyers will easily pass muster. Is it corruption ?
At mature public companies there are people with sign off on millions and often billions of spend. Choice between this supplier or that? Between a factory in Vietnam or Ohio? 100 Million on the nose and his / her signature is the final decision.
There is obviously auditors to catch the worst corruption and a process as to how a decision gets made (usually with an eye on the auditors) but yes. It's that person who makes the call.
Do they do it on a whim ? Unlikely but do they also give a monkeys what the devlead on the third floor thinks?