Hello Boihoaphau32
Welcome to the SBB Community.
We are a customer help page run by volunteers. This is not the SBB customer service.
We are unable to confirm your conclusion as we do not know your intinerary. A 3-days Swiss Travel Pass is indeed more expensive as it provides full flexibility.
I also see that Children under 16 travel for free.
This statement is incorrect and explains why you cannot find free tickets for children. Only children under 5,99 years can use public transit services for free, a ticket is not required for them at all.
Children 6 to 15,99 need a half fare ticket or Day Pass Child, what ever is the cheaper offer.
Children from 6 to 15,99 do travel for free solely
- when accompanied by their parents, and
- if they hold the Swiss Family Card
The latter is (complimentary) only available when you as parents purchase a Swiss Travel Pass or the Swiss Half Fare Card; yet not with point-to-point tickets or day passes.
Alternatively, if you neither hold a Swiss Travel Pass nor a Swiss Half Fare Card, there is the Junior Card which costs CHF 30 per child, valid for a year, which is also available for tourists yet not online but at the counter. It grants free travel when accompanied with a parent with a valid ticket.
https://www.sbb.ch/en/travel-information/individual-needs/travelling-with-children.html
Let us know if you need more help from one of us travel experts.
Kind regards,
Roland