Firstly, California property taxes are limited by Prop 13 to being 1% of assessed value, so your $30k tax bill can only happen if your property went to $3 million. A $1 million house cannot have a tax higher than $10,000.

There are well-established solutions to your issue about people being forced out of housing with rising demand. Massachusetts allows tax deferrals up to 50% of a property value. (If you want to get technical, Massachusetts allows towns/cities to allow tax deferrals; if your city does not want to offer it, they do not have to)

So, your $250,000 -> $1 million dollar house allows up to $500,000 in tax deferrals, so you've got a lot of years you can live in that house without paying taxes. When you sell the house, you pay the taxes and also pocket a pretty sum on the appreciation in the value of the house.