The point was to illustrate that a rise in home prices with stagnating wages, means the effective tax rate for an individual will only get worse under Texas's s

The point was to illustrate that a rise in home prices with stagnating wages, means the effective tax rate for an individual will only get worse under Texas's system, hence, regressive. Whether it's at that tipping point right now, I don't believe thats the case when comparing like-for-like income+property as you rightfully point out. As I understand the source data it also introduces sales/excise taxes which does make it tip over. With more and more people moving to Texas, it's not unrealistic to see more $1M homes.