My ex-husband, who was more mechanical than musical, had the same idea. He believed that the way an orchestra tunes up, each musician tuning his/her own instrument, was "inefficient." I told him that tuning a stringed instrument by the tension in its strings would not work. Other variables include the materials of which the strings are made, the age and history of use of the strings, and presence or absence of fine tuners, which would alter the length of the strings. As I've said many times, I believe it's best to learn to tune by ear.