That's just true by definition of how a price works though, it's not really up to each person to agree or disagree with.
I get that you're not realizing the gains when your house goes up in value. But a property tax is not a capital gains tax, it's a wealth tax on a specific type of wealth (that happens to be very important to society and easy to track). The rules that everyone else is playing by, are that you're taxed based on the value of the property. Whether you realize the gains or not, to give you a break on it at the expense of people who happen to be newer, is not somehow inherently more fair. It's a transfer of wealth that is very regressive on average and goes directly from those with less money to those with more. And it has been a huge driver of the housing and budget problems created in California over the last 40 years.