Most interesting TJW.
This 'fine slicing' of prices is also seen in the mobile phone (Cell) market. They started with three tariffs and now there are dozens. When I renew my contract I have often been told, "That tariff is no longer available" So a tariff that worked well for me, balancing minutes and messages and so on - is removed. Possibly because it was too nice for me?
Utility companies now do the same for electricity and gas.
One objective is ensure that you can never find the same tariff/fare again and that there is little or no direct comparison with the competitors. For, if the fare/tariff is different to all others - then it is more difficult for price comparisons to take place. Of course, many of the differences are in the small print - which do not usually get read. These might be about refunds, rerouting etc.
So, all you can do is look at the price that is presented on the screen at the time you want/need to book and decide if that is acceptable to you. Trying to chase down savings of £/$/€10 or 50 will drive you mad and waste more time than it is worth.