They have backup power at the airport, and no, jetliners are not arriving and departing in the event of a power outage in the tower.

This is nearly the exact reason most 'smart home' systems fail eventually. They become very brittle after the hardware gets 'old'. Where as the dumb tech from the 1950s still 'just works' and costs 1/20th of the smart switch.

In that system you can tell what is going on by looking at in a glance and works with no power. Sometimes simple is a great answer.

However, I can think of one reason the 'no power' argument fails. They do a lot by radio. That needs power. Also you would need to retrain everyone. Oh and you probably would get locked into one company that wants to control the whole software stack and sell tons of support.