Why can bands play for hours often utilizing different instruments without ever looking at sheet music, but orchestra musicians always read from sheet music?

Question

I saw a clip where a pianist was playing and someone was turning her pages for her, but they fumbled and dropped the sheet music. The pianist kept on playing, but it got me wondering why have the sheet music if she knows the song anyway. Do they really need it? Why can’t they just learn the songs like all bands do?

In: 5311

Answer 1

A lot of the responses have made the points that classical orchestras don’t get much rehearsal time for the amount of music they play, and that popular music has more improvisation in it. But an even bigger reason is that popular songs inherently have a lot more repetition than classical music. Lots of songs are built around one or two repeating sections that consist of a repeated 3- or 4-chord loop. Almost no classical music does this, and when it does repeat, it’s at the larger section level, so there are many more notes to remember