It seems to me that affordability starts with housing, because it is usually a household's single largest monthly expense. And it seems to me the best way to make housing more affordable is to make it non-profit. That doesn't necessarily mean city owned or other public housing, nor does it mean tax payer funded or subsidized housing, but having apartment buildings owned by a non-profit organization that charges tenants only enough rent to cover the organization's expenses without any extra going to an owner as profit. And the thing is, non-profit housing isn't only theoretical. It exists right now, but it's relatively rare. The reason is for-profit landlords don't want it because they can't compete.

Let's say you have two identical apartment buildings, but one is owned by a non-profit housing cooperative and the other is owned by a private landlord. The non-profit housing cooperative is going to have the same ongoing expenses (property management, maintenance, etc) as the private landlord, because the apartments are identical, but rent will be lower at the non-profit housing because they charge only enough rent to cover expenses whereas the private landlord charges rent to cover expenses plus some for his own personal profit.