Across the N.F.L. on Sunday, the scenes were familiar, starting long before the games began. Anthem singers rehearsed their renditions in empty places like M & T Bank Stadium in Baltimore, and the words and melody carried deep into the surrounding parking lots, which were thick with revelers and barbecue smoke. When the song swept through, tailgaters continued eating, drinking and playing games, unmoved. It was not the time or place to pause for the national anthem, apparently.

Fans were much more attentive in the minutes before the game, at least in the seating areas. On a large, wide walkway at the open end of the New England Patriots’ Gillette Stadium directly overlooking the field, several dozen fans ambled around during the anthem, indifferent to the song or the presentation of the flag by a color guard on the field.

At MetLife Stadium in East Rutherford, N.J., a steady flow of men entered and exited the restroom during the anthem, though it was audible through the concourse. Of the hundreds who passed near the aisle leading to Sections 103 and 104, a tiny percentage stopped, removed their hats and held their hands on their hearts. People in concession lines continued their transactions.

At AT&T Stadium in Arlington, Tex., where the Dallas Cowboys were playing the Los Angeles Rams, many fans raised their arms during the anthem — some in a fist as a sign of protest, perhaps, but far more holding a cellphone high to better record what the players were doing.

Green Bay quarterback Aaron Rodgers wryly noted the contradictions inherent in the anthem-respect debate when he posted a photograph on Instagram last week, showing photographers crouched at the feet of Rodgers and his teammates, aiming cameras at them.