very much a struggle when the pitch kept creeping up to A 444, even when I was in college. But sometimes you are dealing with instruments affected by humidity and so on. Back in the day....way before you and me, pitch was A438 - if you listen to any recording of music before (gonna guesson this) the later classical era played on original instruments and tried to play/sing along (as I sometimes do when I am trying to memorize), the difference in pitch made it impossible because the instruments were tuned so low. Actually, many of the composers music sounds much "better" in that lower tuning.
Some would think that this would not affect a singer, but you could not be more wrong. A singer practices a piece to "get it into their voice". Singing at a different key than the one that will eventually be performed can be disastrous, especially if the tessitura of the piece is at the top of the range....
I won't even go on about the changes made to the flute....
I could go on and on....