Excellent discussion so far. From my point of view the primary purpose of the 3/4 width is to stress the responsibility to the overtaking driver and to make it easier to establish whether or not sufficient room was given. On my earlier point, I think very often overtaking drivers do not have enough grip in reserve to pinch it tighter to avoid contact. In any case regardless of 3/4, 1, 1+6"...thats not what is at the root cause of contact. The root cause is overtaking drivers attempting low percentage moves. The solution is not making it more difficult to establish fault, nor is it to shift fault to the overtaken driver rather to have consistently applied and escalating in severity penalties. James nailed it. This is my opinion as a driver only. As an official my opinion is irrelevant, the rules as written are what matter lol