Clear operates a line cutting service pretending to be identity verification. DHS can already identity proof at domestic and international checkpoints using biometrics. CBP has processed almost 500M travelers at the border using biometrics.
TSA is more than just the public security line at airports.
It's responsible for all aspects of airport security including all employees, both resident and transient, inside and outside the airport.
What's really baffling is how many different ID and security badge regimes DHS is responsible for, because they areythe exclusive issuer. Each airport issues their own security ID badge (SIDA). There's no interchangeability for identical clearance levels. It's remarkably inefficient. This isn't TSAs fault. Congress is the responsible party, yet rarely does it consolidate anything.