Some speaker wires are custom cut and terminated/soldered and I guess if it was expensive enough you could save a few bucks with different length cables.
However I have OCD when it comes to my stereo with everything being lined up perfectly, no cables touching each other or the floor, etc., so for me they should be equal because there is some electrically measurable difference with different lengths that is not audible, but still "there". That's enough for me. I am sure we've all bought something that was supposedly better that we paid extra for that is not audible or detectable as an improvement individually.