> In a lot of cities property taxes are enough to get in the way of secure housing for, e.g., disabled people.

Nah, the market is supply constrained, if taxes go down the price of the real estate just goes up to fill the gap. People make purchase decisions based on income & total expenses, not on anything else, "can I afford this house?". The price stops rising when the answer switches from "yes" to "no". If your friend can't afford a house right now they don't have enough buying power to compete in the market with other house buyers. Reducing taxes won't give them any advantage in the market that other buyers don't get.