Applicant Authorize Credit Report Check of Co-App?

Yes. If there are co-applicants listed on an on-line credit application, how would you know who completed the information? It's possible both filled it out. If it was one person representing another, the co-applicant could very well be aware and gave the primary applicant the information to submit (very common). If the co-applicant doesn't know about this, then it's identity theft and the primary applicant is wrong. The creditor is not wrong for acting upon the information. If the co-applicant complains to the creditor, the creditor can show the evidence (the online application) to the co-applicant and they can go after the primary applicant for misrepresenting them.