One nation one license for physicians

In today's economy, healthcare spending is one of the biggest driver of cost.
To work as physician, one has to obtain license in the state one wants to practice.
Unlike any other license, physicians have to reapply for state license if he/ she wishes to practice in another state. This is just reinvesting the wheel, increases cost and reduces competition.
Furthermore, each state has its own way of licensing. Some states are notoriously hostile in granting licenses. They have created archaic rules and regulations which delays and sometimes denies the license.
Allowing physicians to practice across the nation will reduce cost, increase competition.
It will not impact quality in any ways, as federal facilities such as prisons, VA already allow to practice if one holds license in any state.