The fiber cut was to the Philadelphia TRACON facility, which is run by the FAA. Also, the FAA runs the towers at airports, unless it's a contract facility. No idea how the infra is handled at contract facilities, but I'd be shocked if it didn't follow FAA guidelines, such that the FAA is dictating the levels of redundancy available.

Also, there's a big difference between a small towered airport in a more rural area, and a major international airport with 10x or more the commercial traffic. So there's probably some difference of buildout depending on the facility usage.

Quick edit: looks like there were two fiber cut incidents recently, one at an airport last month, and the TRACON issue that happened 1.5 months ago!