So someone else put up the capital, the government made that capital cheap, and societal demand with artificial scarcity (in most places) pushed up the asset value.
I’m not saying it’s a bad thing, but let’s not pretend that making capital gains on a house in the US is anything like any other available investment.
Yes, mortgages are subsidized by our interest tax deduction system. That part is true. It doesn't turn home ownership into something with no risk, and it certainly doesn't turn it into this subsidized investment. It's a liability, not an investment.
Just have government allow taxes to be deferred until time of sale with interest pinned to the cost of borrowing for government. That already exists where I live for people over the age of 65. The government can still get the revenue for free via borrowing and the payback is more or less guaranteed.
This doesn't totally automate it, but it takes away the need to manage the proceeds from a reverse mortgage between the time you receive a payout and the time you pay your taxes.