Most courier companies I use have a Google API that allows you to input a destination address, after which the form will tell you how much delivery costs based on ACTUAL DRIVING DISTANCE. We use tiers on our online store when charging customers for delivery, but there are wild differences between actual KMs our couriers need to drive vs what the customer actually paid for through our store. i.e. we have customers who pay for 23KM, when in fact they are 30KM away (sorry, we don't use carrier pigeons to deliver!) .
SQUARE!! Since you're already using the Google Maps API to verify addresses, *please* please please start using the actual "driving directions", and not straight-line radius, when calculating delivery distance!
Thank-you. - David
