In comparing American with British, there are a couple of examples that come to mind. For example theater was once spelled theatre in the US. Under that spelling, it would be pronounced theatra, but it was pronounced theater under both American and British. So instead of changing the American pronunciation, it was far more convenient and logical to change the spelling to theater for that and similar words.
Another example is honour. The u is silent, keeping it can lead to confusion (because it would be pronounced like hour). So it was decided it would be logical to drop the silent u.
But, in spite of rules, languages need to adapt for a variety of reasons.
PhilX