Revenue. An article about permitless open/concealed carry of firearms in Oklahoma included this final line:
“State agents said they’ll adapt to the changes. But because Oklahomans won’t have to pay to get a permit anymore, the Oklahoma State Bureau of Investigation could lose between $4 – $6 million in fees.”
Yeh, “concern” over milking citizens for more money is certainly one reason. Of course, a strong desire for state control over citizens’ inherent rights is prevalent as well.