Require employers of each H1-B to submit (along with the hire's w-4 that they send to Uncle Sam that already includes the job's wages and benefits), the position description in the job ad, the candidate's resume, and the matching wage band the job purportedly falls into and exceeds by 20% (or whatever the required margin is). It should be trivial to automate the validation process. Then do random checks to confirm those purported facts, especially of employers who hire large numbers of H1-Bs and have past violations.