Let’s look at wealth.
For a working man, or woman, most of their wealth is represented by their homes. Homes are the single biggest component of their wealth.
A rich person’s wealth is distributed across various investment vehicles, not just their house. Equities. Bonds. Art, jewelry, and cash. None of that is subject to property tax.
A member of the working class may own equities, bonds, art, and jewelry, and cash. But all of that is likely a much smaller proportion of their wealth portfolio.
Houses are subject to property tax. All that other stuff is not.
So, a member of the working class pays a higher percentage of his income in property tax than those whose wealth is distributed across various investment instruments.