The point of using spaces is to not worry about any of this. You need a specific fix for less, another specific fix for other diff tools, etc etc. With spaces, everything just works.
I don't see it as a "fix" but as a configuration. And tabs also just works, if you accept the defaults that are given to you :) but if you don't, then you can change your settings (which is trivial). With spaces you have no option but accept whatever is given to you.
