The incidence of property taxes has been the subject of academic conjecture for at least 4 decades, yet there are virtually no empirical examinations. The only two I can find in the last 25 years that I can commend are one from 1994 by Carroll and Yinger in Boston, who concluded that only 15% of any property tax is passed through to tenants, and a large 20-year study recently concluded in Germany where it was concluded that, in the short-run, landlords absorb all or substantially all of any property tax increase, and are only able, over the long term, to pass through to tenants some of it where and when rental housing demand exceeds rental housing supply. So there is no support I can find for anything close to the allocation made to tenants in the ITEP study, which is obviously a very significant part of their portrayal of a picture of inequality.
And as a closing point about the biased nature of the ITEP model, please note how its disparate allocation of property taxes vs its disregard of the services typically paid for with property tax revenue, i.e., education. As pointed out above, the model allocates zero income to households for schooling children. Yet it allocates to renters 50% of the landlord's property taxes. That is a sure way to make the distribution look regressive: allocate costs but not benefits. Unfortunately, that is at odds with the most basic principles of financial presentation: match the person's or entity's income and expenses. Here, the organization deliberately chooses to separate them, which is a big driver of the portrait they create.