Perhaps you should consider that your old, $250 billion company is going to be a bit more formal than a young, $50 million company.
If your company really does have a purchasing proces so rigorous that it will reject an "IT" contract signed by the CFO despite it being within their purchasing limit, then there's a reason for that. The reason typically being that in the past there was enough naughtiness by some CxO that they went to all the trouble of putting some heavy bondage into their purchasing rules.
Also, I would be willing to make a cash-money bet that CxOs shopping outside their domain authority don't get immediately fired for that. Even at your company.
Yes, you are right, they are not immediately fired; they "retire" immediately or leave the company in the next few months. In the past month we just "retired" a few directors and another one is "just leaving" in 3 months, until then his spending limit is revoked and he is just onboarding the replacement.
If your company really does have a purchasing proces so rigorous that it will reject an "IT" contract signed by the CFO despite it being within their purchasing limit, then there's a reason for that. The reason typically being that in the past there was enough naughtiness by some CxO that they went to all the trouble of putting some heavy bondage into their purchasing rules.
Also, I would be willing to make a cash-money bet that CxOs shopping outside their domain authority don't get immediately fired for that. Even at your company.