I agree, it does appear to be nosy, but a prospective employer is unlikely to use that information alone in making a hiring decision. And they can only run the credit check if you say it's okay. A credit reporting agency can't supply information about you to a prospective employer without your consent.
The introduction below is taken from an article titled "Credit Reports and Job Hunting" By Les Rosen, Employment Screening Resources Reprinted from HR.com. I've posted the link below if you'd like to read the entire article.
-----------------------------------------------------------
Many job applicants are discovering that employers require pre-employment credit reports before they hire. For many companies, a credit report has become a screening tool to evaluate a candidate and to exercise due diligence in the hiring process. But for job applicants, a credit report can feel like an invasion of privacy or a violation of their rights. However, job applicants have substantial legal protection concerning the use of credit reports for employment. In fact, an employer cannot obtain a credit report without an applicant's written permission and cannot use it to deny a job until the applicant has had the chance to review the report
Employers seek credit reports on job applicants for a variety of reasons. Some employers utilize a credit report to verify that an applicant is responsible and reliable or to confirm identity. Other employers are concerned about hiring persons who cannot manage their affairs, or whose monthly debt payments are too high for the salary involved. Many employers limit credit reports to management and executive positions, or to positions that have access to cash, assets, a company credit card, or confidential information. Employers are well advised to run credit reports on bookkeepers or others who handle significant amounts of cash.
However, employers should approach the use of credit reports with caution, and have polices and procedures in place to ensure that the use of credit information is both relevant and fair. An employer should first determine if there is a sound business reason to obtain a credit report. Unless the information in a credit report is directly job related, its use can be considered discriminatory. For example, running a credit report for an entry-level person with low levels of responsibility or no access to cash is probably not a good practice. Unnecessary credit reports can discourage applicants from applying, and running mass credit reports on all applicants, regardless of the position, can have the effect of discriminating against certain protected classes. In addition, employers should avoid making negative hiring decisions on information that is old or relatively minor.