That's the interesting thing, Mutt ... Oz is the only State (so far as I know) to have implemented demonstrated runway width capabilities .... the penalties arise due to the conservative nature of the approach to the test problem .. at the low speed end ... but, make no mistake about it ... my preoccupation, from time to time, in threads on Vmcg and crosswind .. derives directly from seeing the sort of centreline deviations during runway width test programs ....
Guess that the other States figure that the risk of a failure under critical conditions is a fair risk ... but have that failure and you should expect to roll the wheels in the mud off the side of the runway.