Consider property taxes in light of this (paraphrase from Rerum Novarum, Leo XIII:

The working man's little estate should be at his full disposal.

...if a working man invests his savings in land, the land is "only his wages under another form" and that he has "as completely at his full disposal" as are the wages he receives for his labor.

...the working man's estate, whether it be land or chattels, should be in his full control, allowing him to use and dispose of it as he pleases.

The idea is that the working man's labor and savings should be rewarded with a property that he can use and benefit from as he sees fit, rather than being restricted or controlled by others.