Makes sense to me. I've a TNW abo. If I go to Bern on a train that goes Basel, Liestal, Olten, Bern, I can buy a ticket from Liestal to Bern for that segment. If it doesn't stop at Liestal, I have to buy the ticket from Basel. The trains that don't stop at Liestal cost more from Basel than those that do. The price for using a faster train.

So I don't see what the issue is. Did I miss something?

btw - typical Swiss. "Bad English" indeed. I wish my German was as "bad".