Hello Allenjames
It must be clear that apples are being compared with oranges here.
Or in other words, you are comparing Supersaver tickets with national ordinary tickets and zone based Mobilis fare network tickets. They all use different price calculations, the latter are even subsidized tickets by the canton of Vaud.
The Lausanne to Aigle train does not offer saver fares for this connection, this is why you cannot purchase a Supersaver ticket for the entire journey in one ticket. Also, a ticket cannot include multiple ticket types unless you split your journey.
Simply purchase the ticket combination that suits you best. Keep in mind that Mobilis tickets are timely limited, the ticket validity start date must be after your arrival in Lausanne.
Kind regards,
Roland