Hi Colin. It would be great to do things like this with Google - we used to have driving instructions that worked to get to the start of every route.
The technology exists. However, these days it's prohibitively expensive for a busy website like Walkhighlands to make the calls to Google for routing etc. This is why we changed our start point links so that they actually take users away to Google Maps, rather than a page with functionality on Walkhighlands. This means users can easily see how far away it is, access driving or public transport, etc. without us having to pay Google for that functionality.
For the same reason, our
walk search relies on distance from any postcode or address (or simply where you are) from our own server-hosted location database, and works by distance as-the-crow-flies as accessing data using roads would be involve expensive calls to Google.
Hope that makes sense.