Do all houses have interior load bearing walls?

The simple answer is no. There a number of considerations to determine if laod bearing walls area required.

Type of house and amount of storys.

How the first floor is actually supported and is beneath open plan or not. Are Steels used (RSJs) to support the first floor so that the expanse is covered acoss the whole building. In these cases the steel is normally strong enough (bearing in mind the expanse ) to support a floor above.

Building codes in the area where the building is

Types of wall structure i.e. brick, block or wood