Came about after 9-11-01, when the B. Jr administration wanted EVERYONE to join in the patriotism and back the troops while him and Cheney (Halliburton) sent the military into the mid-east to eliminate perceived enemies and steal oil and or massive amounts of tax dollars.
All pro sports games played the national anthem, but it wasnt the spectacle it is and has become. TV never showed that part of the games except for maybe the Superbowl. Not sure about basketball and baseball, never watched those championship games.
I wonder if anyone will ever know how many tax dollars were sent to the NFL, MLB and NBA to highlight military members. When my wife and I were season ticket holders for the Cardinals, every game they would highlight a service member and show them on the big tvs and every one would applaud.
I remember there was some sort of outrage (however small) when it was found out we were paying the NFL to do these things.
I also always wondered how much was sent to video game developers to fund first person shooter games for young kids to get hooked on and desensitize them to war
but thats another thought outside of this OP
Cheers,