Ah, perhaps you don’t understand how Prop 13 works.
If a person bought a home in 1978, for instance, their property taxes are 1% of the price at the time of purchase, plus a 2%/year maximum increase.
Another person can buy an identical house next door to the one above for 3X (or 10X+) the price of the house purchased next door, and their property taxes are assessed at 1% of their purchase price, plus the 2%/year max annual increase.
So, you can have two identical houses where one owner is paying say $1,000/year, while the next-door neighbor is paying $10,000/year. Now do you see why this is a subsidy?
Now, I don’t mind doing this to help out the elderly neighbor (or any owner-occupier who owns and lives in only that one house) so that they aren’t taxed out of their home, but I’ll be damned if I’m going to pay a higher tax bill than the landlord who is pocketing this entire subsidy for no reason.