[potato3732842]

Most states just outsource licensing to a professional organization and transfers are a simple matter of filing a form and paying a fee.

If practicing across state lines is lucrative there's not much stopping existing listened professionals from doing it.

[hellotheretoday]

the professional org handles certification exam and varying amounts of paperwork verification depending on state but every state has a licensing board to make the final determination and handle grievances

Further, transfers are not always as simple as you describe. Sometimes they are. It depends on the states