Utility power redundancy isn't subject to the same kind of regulations that aircraft systems are. It's cheaper to provide backup at the systems identified as being critical (comms, ILS, ATC, terminal fire suppression, etc.)
It's possible to build in redundancy, if you are willing to pay for it. But even then, unlike aircraft power systems, there are too many engineering and operations groups involved (local utility, regional power agency, terminal landlord and customer) to properly communicate the failure modes and effects back and forth through a design process..