Imagine, for a moment, that I'm a literalist. Which exact part of the constitution prohibits them?
> The government should not be able to force private companies to do the work of LEA.
Good thing they aren't tasked with the work of an LEA, they simply have an obligation to report what they know.
But even if they were, there's nothing that precludes the government from conscripting people for service to the state (The draft). Or from empowering third-parties with LEA-like powers (Bounty hunters, for example).
Are those also prohibited by the constitution? Which part of it?
FWIW KYC "laws" are unconstitutional garbage. The government should not be able to force private companies to do the work of LEA.
And before you inevitably reply about how "it's good because it's stops XYZ"
1) It doesn't "stop" XYZ
2) I don't care, privacy and freedom are more important than catching a few more % down the long tail curve of bad guys.