Known Traveler Digital Identity system is a "new model for airport screening and security that uses biometrics, cryptography and distributed ledger technologies."
Blockcerts are for academic credentials, AFAIU.
[EDIT]
Existing blockchains have a limited TPS (transactions per second) for writes; but not for reads. Sharding and layer-2 (sidechains) do not have the same assurances. I'm sure we all remember how cryptokitties congested the txpool during the Bitcoin futures launch.