Fact #1: The players were NOT on the field for the National Anthem until 2009... From the beginning of the NFL until then, the players were inside the locker room....
Fact #2: As the US Military (DOD) wished an increased show of patriotism at games, they agreed to pay the league an average of $300,00 per team. If one considers how many enlistment ads are shown by the military this seemed to make sense.
Fact #3: I have yet to hear a single owner agree to return those funds and to allow the team to return to the old pre-2009 rules.
They don’t need to return the funds, the agreement with DOD was not renewed prior to last season, all showing of the anthem since then has been at league/ network discretion.