It's total nonsense.
The fact is that the majority of these postcodes are mainland UK. Companies that offer free delivery to mainland UK should also include all addresses that can be driven to without resorting to a boat or plane.
REMOTE LOCATIONS ARE STILL MAINLAND UK
Royal Mail are obligated to charge the same for delivering a letter from London to Orkney as they charge delivering a letter from Newcastle to Manchester and couriers should do the same.
To say that Londoners subsidise deliveries to the Highlands is naive at best. Those in areas of large population do indeed subsidise deliveries the Royal Mail makes to remote area. However with the Highlands only accouning for less than 0.5% of the population of the UK, the subsidy is very, very small. I doubt even 1p on a stamp.
Most of us here in the Highlands (yes we have roads, elctricity & running water) have got used to paying a bit extra, and thats not the real bug-bear.
What really sticks in our gullet is the companies advertising a service and not following through on it. Not only that, but they then double or even treble delivery charges. There is absolutely no justification for the disproprtionate charge. On several occasions we have been quoted more for delivery than the goods are worth.
And while we're trying to say that we should pay more because we're remote, consider the like of Homebase or Argos. If you buy article X in London for £Y, it costs exactly the same in Inverness Homebase or Argos - despite the fact that Inverness is miles away and the store obviously incurred extra charges.
Companies that do care will sometimes swallow the extra courier charges, or will offer to use Royal Mail or Parcel Force. Those that do are more likely to get repeat business. The companies that are disinterested, well they are not worth bothering with as customer service features very low on their priority scale - and why would you want to continue to support them.
YANBU however there's very little you can do about it. Name and shame might help you let off a little steam, but in the long run it will make no difference at all.