In 1936 American Standards Association (and the International Organization for Standardization in 1955) accepted that A would be tuned at 440 Hz (or cycles per second). Yet despite the fact that a standard has been accepted, orchestras frequently deviate from this standard.
The San Francisco Symphony (reportedly) tunes to 441 or 442 Hz
The Boston Symphony Orchestra (reportedly) tunes to 444 Hz
The New York Philharmonic (reportedly) tunes to 443 Hz
and The Berlin Philharmonic (reportedly) tunes to 445 Hz
I know there's a tendency for some European countries to tune to 442 Hz and German orchestras are among others who tune to 445 Hz. But what makes an orchestra choose one of these numbers? Who makes the decision, the orchestra's leaders/committee or the conductor? What is the point of making this distinction? Why, after standardizing a tuning system, go to the trouble of changing it by so slight a degree?
(For the sake of this question, let's not take into account period instruments or ensembles which are famously tuned to anything from 415 Hz to 490 Hz)