How do you suggest we get a yearly appraisal? Do it ourselves? Or pay an appraiser? In the case of the former, it's not worth the trouble (to me). In the case of the latter, it's not worth the cost. Same goes for the cars. It's trivial to look them up on Edmunds, but I don't need that level of detail. I'd rather have a conservative estimate of what I'm worth, as opposed to assuming that I'm willing to liquidate a car or our house to free up cash.
If your tax assessor doesn't provide you with an estimated property value, you could look up comparable home sales in your area and use that as your approximation. I agree that it's not worth the money to pay for an appraisal. As for whether it's worth your time to make the estimate yourself, that's up to you.
I think the key concept in your response is your need for level of detail. Although it's trivial to look up the price of a car on Edmunds, that's not exactly the value of YOUR car, so you're already making an estimate. As for the house, I receive a yearly appraisal from the property district (upon which my taxes are based). That too is just an estimate, as it's not to the level of detail a buyer would want. Long story short, by including house & car, my net worth calculation is based on two estimates and is therefore only approximate. (More, if you include checks floating out there and credit card transactions for which I haven't yet been invoiced.) But since the relative change
is what's important to me, I'm ok with the approximations.
By including home & car, I'm not necessarily saying I'm willing
to liquidate either to free up cash though. They are assets, that's all. It's the accountant in me that wants to include everything on the balance sheet.