I heard that idea attributed to Heinlein many years ago from a friend who read everything he wrote.
A few downsides I thought of
1. It makes it easier for rich people to do mean things to poor people (it's not like there aren't already lots of ways, but something to think about)
2. In rapidly changing conditions, people who neglect to file their paperwork will get screwed -- either significantly overpay or get kicked out of their houses for below-market values. The people who are neglectful in paperwork are probably disproportionately those that we typically aim to protect with government interventions
3. Eminent domain changes a bit; people would naturally price their houses for above-market values, because being forced to move unexpectedly is a hassle, so you would assess your value at a premium to avoid that hassle. This means the government would likely have to pay more for property than the "fair market value" that courts require. Depending on where you fall on the political spectrum, that may be okay.
4. Holdouts[1] tend to be popular. Making it financially untenable to be a holdout thus might be too unpopular a law to pass.
A few downsides I thought of
1. It makes it easier for rich people to do mean things to poor people (it's not like there aren't already lots of ways, but something to think about)
2. In rapidly changing conditions, people who neglect to file their paperwork will get screwed -- either significantly overpay or get kicked out of their houses for below-market values. The people who are neglectful in paperwork are probably disproportionately those that we typically aim to protect with government interventions
3. Eminent domain changes a bit; people would naturally price their houses for above-market values, because being forced to move unexpectedly is a hassle, so you would assess your value at a premium to avoid that hassle. This means the government would likely have to pay more for property than the "fair market value" that courts require. Depending on where you fall on the political spectrum, that may be okay.
4. Holdouts[1] tend to be popular. Making it financially untenable to be a holdout thus might be too unpopular a law to pass.
4: https://en.wikipedia.org/wiki/Holdout_(real_estate)