Also, some bike manufacturers use the same parts for ALL SIZES of the bikes. For example, a female friend of mine bought a 54cm complete bike. She's 5'4". The bike came with 44cm bars. 38-40cm bars would have been more appropriate. But, it was probably cheaper to put the same bars on all of the bikes in the range.

Without a fitting, she would have not known what bars are right for her. She switched to 39cm bars and was very happy and comfortable.