The reason is very obvious. In Spanish one says that the sneaky deal was done under the water, but in English one says the sneaky deal was done under the table. They both mean the same, but the Spanish person understands the phrase if you use "under the water", and the English speaker understands the phrase if you use "under the table". If you translate the Spanish literally word for word into English, it won't be comprehended by English readers. So translating from one language to another is problematic. Word for word leaves much that is unintelligible, and thought for thought leaves doubt as to which is the correct thought precisely. The Hebrew word Chesed is translated mercy, but the word means more than a single English word can capture. Another thing the King James does is translate the same Greek word using a variety of English words. For example, In Romans 4, logizomai is translated counted, reckoned, imputed depending on the context. Correct translation in every one of those verses should have been consistent, whether Counted or Imputed or Reckoned, just one of those should have been used. In Greek there is only one word used for those verses. King James is my beloved study Bible along with a whole host of Greek and Hebrew helps, but I can not say it is perfect and remain honest. However, I believe it beats anything out there.