I would suggest that the observation (not set up as an experiment, but by chance offering a large scale observation of actual behaviour as if an experiment was intended) is capable of extrapolation. Whenever suppliers are price takers (as in competitive markets they should be) taxes on suppliers will always be paid by suppliers and the suggestion that they are passed on to others makes no sense at all. This is now seen to be true for rents. I think it will be elsewhere.
So the next time you hear some rightwinger argue that tax is not paid by capital but is passed on to consumers or workers just note that what they are actually saying is that there are non-competitive markets in existence and that this fact should be their real focus of concern. But oddly, it never is. Right wingers are the last people who want competitive markets. They do not permit abuse, after all.
He’s confusing “capital pays this tax” with “capital pays all taxes I think should be incident upon capital.”
Ritchie is, himself, insistent that employer’s national insurance is actually incident upon wages. Who pays the tax thus being a question of “it depends.”
Plus he’s missing what the damn point was in the first place. More taxation of landlords will mean fewer landlords, thus fewer places to rent an thus higher rents. Could happen too – and pointing to rents falling doesn’t change that. Because that’s to ignore ceteris paribus, something we never should in economics.