The FCRA does not apply to all situations. You can't ask for DOB . There are states that do not require background checking companies to be licensed. However, with the contemporary emphasis on privacy, one can expect the remaining states to adopt the requirement of licenses for background checking companies in the near future. However, that is not your main concern.
Most states do require licensing.
When you do a background check on a person, you don't know ahead of time where the paper trail will lead you. You could require a record from any state in the U.S. regardless of where you are located. And if you use an unlicensed firm to obtain a record from a state that requires licensing, most likely that record will not be admissible in a court action as it will be deemed to have been obtained illegally. You screen to avoid problems. However, you never know which employee may be a problem down the road.