> I didn't say force. I said incentivize.
Incentivize usually means offering something to someone to make something attractive.
That is not what you are proposing. You are proposing to take away her money by force until she can’t afford to live there.
> If her property taxes aren't artificially constrained by prop 13
Taxes that rise based on a tax inspector estimating the value of an unsold property are at least as artificial as taxing based on transactions. There is nothing ‘natural’ about property taxes. It’s a system constructed and imposed by the local government.
> she'll see her taxes go up over time
Yes, through no fault of her own, if and only if other people continue to drive up prices.
> and decide how much she values staying in the house and paying the increasing taxes
Agreed. If other people drive up the price, they’ll be able to force her out of her home.
> Society benefits from incentivizing her to move, so that more humans can occupy the space she is currently occupying, which will improve regional productivity, reduce highway and transit overcrowding, reduce greenhouse gas emissions, all sorts of good stuff.
A kinder way would be - why force grandma to move, when not doing so would bring all of these benefits to areas which need them more, and frankly, have better incentives in the form of currently lower costs?