An Australian think-tank has proposed a radical solution to the supposed "housing crisis" - tax people for unused bedrooms.The thinking is simple: There are many people, mostly older couples whose children have left home, living in family-sized homes with one or more bedrooms sitting empty. If the state were to impose a tax on unoccupied bedrooms, whilst abolishing stamp duty, they will incentivise those people to sell their family homes and downsize, thus freeing up homes for young families looking to buy.