Nothing because that isn't inherently private property or at least by Mutualist definitions it isnt... I follow a theory known as occupation and use which allocates land rights to the individuals that work and use the land thus and individual laborer and his family would have every right to have a house on land that they are individually creating output and labor from... The small business one is odd because Mutualists disregard the idea of private business in favor of worker cooperatives so yeah, the small business is still exploiting an individuals labor