That is negligence, practical if not contractual.

Over ten years ago, my employer was spinning up a new DC across the state and had three links between it and the primary DC. Two were pretty direct, but we needed a third because at one point in the 300 mile path, the two main links went within 400 meters of each other.

So how national-security-adjacent critical systems like an airport system doesn't have a larger set of backup links, and validates that they are geographically separate up until the connections, and have realtime alerting on the connection status, is surprising to me.