Not quite. Retired people have deferred income in IRAs and 401(k)s that can be claimed at their leisure after 59.5 years old. So if you deferred taxes from a high tax State and then get the income in a no-tax State, you saved on taxes.

Florida's property tax rate on average, according to Google is 0.79%. Average home price is $411,000, for property taxes of $3,200 per year.

That doesn't seem insane compared to say California with 0.71%?

Depends on what you mean by retired. In the traditional sense you’re correct, retired people don’t have income. In the legal sense retirement just means the person is of age to collect benefits. But there is also the question of type of income.

If a retired person owns property and sells it, that is income subject to capital gains tax.

If a person is retired but still owns the business or is even still a board member, they’re still working in a sense and gaining shares.

There are plenty of “retired” people who are “working” and have income.

New York state has a number of exemptions for property tax for seniors (65+), which seems like a better mechanism than California's prop 13.

Income from Social Security benefits and 401(k)s are taxable.

Depends how much money you retired with. When the ratio of your net worth to the cost of a house is high enough, property taxes are trivial. Let's say you have $50 million and you earn 7% a year on that. That's $3.5 million a year. Well worth it to live in FL to save the $350K you would lose every year in NY / CA.