[Developing countries] When there are considerable economic inequalities, indirect taxes on income and wealth exert less restraint than direct taxes on socially wasteful consumption, yet the majority of developing countries collect 70% or more of their tax revenue from indirect taxation (customs duties, for example). In addition, exemption levels tend to be higher than they need be. In some developing countries, personal incomes up to a multiple of ten or twenty times the average per capita income remain altogether exempt from income tax (compared with from one to three times in developed market economies). In particular, the tax shelter enjoyed by wealthy landlords is an obstacle to overall economic progress.
2. But these advantages can be attained only if private wealth is not drained away by crushing taxes of every kind. For since the right of possessing goods privately has been conferred not by man's law, but by nature, public authority cannot abolish it, but can only control its exercise and bring it into conformity with the commonweal. Public authority therefore would act unjustly and inhumanly, if in the name of taxes it should appropriate from the property of private individuals more than is equitable. (Papal Encyclical, Rerum Novarum, 1891).