Because life with horses is never orderly.
Ah, if only our equine partners could understand language and possessed verbal skills. While I'm positive I'd rather not have to hear how measly their rations are or how they'd prefer not to work today thank-you-very-much, it would be nice if we could just explain to them verbally exactly what we're trying to get them to do. I'm sure it would clear up quite a bit for all of us involved. ;)