The problem is it works badly. You have to open the app which has to load and then you can get access to your key. But if you’re on an elevator then you might not have service and the app won’t load and then you can’t get to your key to use the elevator. Or worse if you don’t have great service in the corridor.
It needs to work in a way where the key is saved to your phone so it can be accessed quickly and offline.
Afaik the HID Global app saves a key in the OS key store (at least on Android) and uses the locally stored key with NFC so you just need network access to enroll a key. Not sure what vendor/app these things use (maybe it's all in house)
Some hotel chains like Hyatt support nfc keys in Apple Wallet. Because whatever microcontroller runs that is low-power, it can continue working after your phone battery is (nearly) dead too.
I know other locks use Bluetooth from an app which isn’t supported by Apple Wallet.
It needs to work in a way where the key is saved to your phone so it can be accessed quickly and offline.