There are 2 non precise bushing surfaces meeting, there .

The bike will still stop, I expect , so this skirts into the.. SO ,
what do you have to spend to resolve this?

if you want them to be Precise , then
a likely solution is to machine the Brake Boss' to a tighter tolerance
before putting it on the frame, and having the brake bushing itself
also to a tighter matching tolerance.

Or Like Paul has done, their Bushing adds a 3rd part in between the frame fitting,
and their V brake so they have a better control of the way the brake
fits on a part of so many bikes,
where the frame boss is not able to be madein such a controlled criteria..


There is the Magura solution, too, their Hydraulic Rim Brake uses V brake Frames
But the frame Boss Is a an anchor point, but not as a Pivot.

I found the Scott Peterson SE calipers .. also are a design
where the helical core , goes around/over, the (cantilever) boss,
but it is clamped in place, and the brake rotates around It.

so all the parts that rotate, in contact with each other
are made to mate together, under the same Mfgr's roof.