Have you ever wondered why some guitars have string trees and others don't? Or have you ever thought, what are these string trees for? Usually guitars with a Fender style headstock will have string trees and guitars with a Gibson style headstock will not have string trees. The reason has to do with the headstock angle. Gibsons like the Les Paul, ES-335 and SG, have an angle on there headstocks that allow for the strings to bend backward. Fender guitars such as stratocasters and telecasters have a straight headstock and compensate for the lack of string angle with string trees. They both have their plus and minuses, but if there is no break in the string angle past the nut, there will be buzzing on the strings.
There are also staggered tuners that compensate for the lack of string tree.