The use of a recording is typical in big events. In 2009, cellist Yo-Yo Ma was questioned about “hand-syncing” for Obama’s first inauguration. Ma said instruments weren’t functioning properly in 19-degree weather.
Even in good conditions, producing good sound can be a challenge in a large open space.
Some artists choose to lip-sync. Whitney Houston’s memorable performance of the national anthem in 1991 at the Super Bowl was sung to a track.