Why doesn't BLS use data directly from Social Security?

Everyone with a W2 pays into SS. SS also has everyone's birthdate, so it's easy to bucketize everyone into "can work" and "can't work."

They can join that with Medicare/Medicaid data to find people with disabilities. The can compare pay periods to see who's unemployed etc. They can find people on disability with help from Medicare.

Why is BLS waiting for state data? To find the unemployed and collecting?

And the IRS. Why is this downvoted?