Before 1945 in the UK, this quote certainly rang true. For many Britons, they were at the mercy of landlords. Without owning any, or much, private property themselves, they were at the mercy of landowners and employers for their own survival.
The extent of the consequences of inequalities in private property stopped ringing true afterwards due to two reasons. The first was in the post war consensus a lot of land was nationalised and turned into council housing which allowed many who initially didn’t own land to get access to land. The rise of social democracy as the political consensus in Britain meant that the necessities of life were spread more evenly among the population as a whole. This though was backed by a large state influence in the economy, when capitalism firmly changed from the one Proudhon had envisaged when he was alive.
The second reason was that Thatcher in the 1980s encouraged the policy of household democracy, in which council homes were sold to the public making the public the sole owner of their home. This reform made ownership of private property more egalitarian than before the second war. However, this reform did not prove Proudhon’s quote wrong despite the expansion of private property in the economy.Poverty level grew heavily in the 1980s. This was linked particularly by those who did not benefit from the expansion of private property, either because they didn’t own a house or they had a job in an industry that the market felt inefficient.
The trend though seems to be firmly in favour of the conditions that this quote refers to coming back. The price of housing is already ridiculously expensive and will only get more so in the next few decades. Many on low incomes are renting under conditions beneficial to the landlord rather than the tenant, primarily due to the way tenancy laws operate in the UK. The number of people homeless is on the rise, discrimination against the homeless is on the rise. Lots of housing is wasted away by nobody using it. Ensuring that the homeless stay homeless despite land being available or them to use.
Ultimately, state intervention has mitigated the effects of unequal distributions of private property to hide the already existing consequences, as described by Proudhon, from the public. The system is unjust, but why it is unjust is not clear to see for all. So far Mutualists and Georgists have managed to find out what is unjust, they just haven’t been able to popularise it.