They are in child seats, the Yuba is a great bike that is rated for over 700 pounds and has lots of child friendly adapters.

You can see more examples of parents pushing their kids in cargo bikes here:

https://www.youtube.com/watch?v=2Yy3kXIaKp8

Without electric it can be a real workout, but with electric assist its so much more fun. The kids cry these days if we tell them they need to go into the car.

You can buy a Yuba with Electric from the company, but its 5K which seemed way too much when you can do it yourself for 1/2 the price.