I would like to say that I really like this idea of zero waist home, but as a designer I would like to give some sugestions.
I think it would work better if you were having a smaller place and more multifunctional furniture. For example, the sofa bed you have in your living room is a good example, but, why two beds in the kid's room? When you can have two in one and change it for a play area or a desk after they are awaken? Or hidden walls where you can take extra beds, or a chair where you could put some books (not a lot, but the ones you really like or use) even though its library books and you will give it back after, at least you will have a space to put them, or a chair that could become smaller or bigger according to your needs? And for the cars maybe you don't live in a big city and you use the car quite often. But the future at least in big cities i believe all the petrol cars will be left in the entrance of the cities (to avoid polution) and everyone will move in public transportation or renting bicycles and electric cars (you can see this kind of car in paris for example). Two cars it's maybe a bit unnecessary.
This is Bea's husband Scott - to answer your questions:
1. Why two beds? Because we have two boys who are 11 and almost 13...I don't think 1 bed will work for them...in fact we will probably get rid of the play room soon, so that they can both have their own room and a little privacy.
2. We don't have a desk at all - all homework is done on the kitchen table - The same place where Bea does all her writing...
3. We use the public library extensively - so no need for book shelves - we are constantly checking out new books and returning books when finished.
4. I agree that there is a big shift in personal mobility - lots of interesting carsharing and ride sharing companies now...in fact, we would like to use those services - but they do not make sense in a small town like Mill Valley. We only have 1 car - and I use it 2 days per week to commute to my work (there is no public transport option available).
Thanks for the questions - Scott