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

Bands (such as rock bands for example) are constantly playing shows, recording and rehearsing their music, so it ends up becoming memorized and they can play while deafened and blindfolded (exaggerated). Also of note, rock band (still using as an example) music is quite a bit more simple compared to large orchestras.

Orchestral scores are more complicated and aren’t played as often, sure the musicians do
rehearse and practice but given the complexity of the scores, they have to have the sheet music in front of them to follow.

Aside from complexity, there’s also timing. All the musicians have to be on time with one another so the score can flow as the composer intended.

Caveat; this is how I understand the differences, however I am open to correction if any of it is incorrect