We have a similar issue in the UK since there are large houses being occupied by older couples whose children have left. Since annual property taxes are low (~4k - we call it council tax) and tax on buying property (stamp duty) is high, there is no incentive to move to a smaller place.
It was nothing other than a massive subsidy for the most wealthy as the top band is reached so early - it's only slightly less regressive than the poll tax was. The Tory campaigns were built around how "unfair" it was for the old widow or couple, who'd worked all their lives, to pay the same as a family of 5. No mention that no one in their right mind thinks a widow still needs a 4 or 5 bed house.
Double bonus: In bringing in council tax local finance could be massively further centralised, weakening the regions even more.
It's really surprising how little push there is to get shot of council tax, bring back rates or some properly progressive tax.