There is no reason why:-

A. it can't be "adaptable" to other regions in the world where postcodes interface with geo-mapping.

B. it incorprates a component that factors weight into the equation.

UK Postal charges are notoriously complex (Royal Mail), but we have recently conducted negotiations with several (8 actually) private couriers, who calculate their rate principally on DISTANCE.

As we all know... shipping calculation remains one of the most hair-pulling aspects of modern catalogue-based commerce.

Short of praying for a solution from above, I think a concerted effort to look at how we can amalgamate the core variables in shipping:-

Volume
Weight
Distance
Value

into a functional, customizable module. we'll be addressing some of the most pressing concerns of e-shop owners world wide.

Zen Cart - leaders in e-commerce would significantly enhance their (already gilt-edged) reputation if they could get their heads around effective shipping configuration...

There must be hundreds of zen cart users with appropriate technical ability to get this in motion. By working in collaboration with the core team (and all users helping to fund it) we could nail shipping issues down once and for all...