Matthew Poole and continuators on Leviticus 25:30

30 And if it be not redeemed within the space of a full year, then the house that is in the walled city shall be established for ever to him that bought it, throughout his generations: it shall not go out in the jubile.

The reason is from the great difference between such houses and lands. The reasons before alledged for lands do not hold in such Houses, there was no danger of confusion in Tribes or Families by the alienation of Houses. The seller also had a greater propriety in Houses than in Lands, as not coming to him by Gods meer gift, but being commonly built by the owners cost and diligence, and therefore had a fuller power to dispose of them. Besides, God would hereby encourage persons to buy and possess Houses in such places which frequency and fulness of Inhabitants in Cities was a great strength, honour and advantage to the whole Land.