I remember seeing numbers for London, where the "story" that gets regularly regurgitated that half the town is empty (ok, so I'm exaggerating a bit) due to the Chinese buying investment properties that they for some strange reason supposedly leave empty rather than renting (which would be particularly strange in the UK, which, though squatters rights have been curtailed still is one of the most risky places to leave property empty).
Except the numbers showed vacancy rates at similar levels in expensive, "investment friendly" boroughs like Kensington and Chelsea compared to boroughs where large portions of the rental market is social housing where the council gets tenants in ASAP after cleanup/refurbishment.
I'm sure there are areas with problems, but many pleases it seems to me that the problem is more one of flawed assumptions. E.g. articles about the situation in London have more than once talked about dark streets and no children out playing.
But if there is one thing that has always been different between rich and poor areas, it is density and likelihood that the occupants will be spending money on activities away from home vs. playing around the block. I remember that distinction well even from growing up in Norway with class distinction far flatter than anywhere in London - the "normal" working class neighbourhoods I grew up in were lit and surrounded by kids playing outdoors in the evenings, while e.g. when I went to visit my grandparents in one of the wealthier parts of town, it was always darker - the flats in their building all had two living rooms and a couple of bedrooms with windows facing the road, and more rooms facing the inner courtyard. Even when people were home at night, there would be far less lit windows for the simple reason there were not enough people there to use all the rooms at once.
It seemed to me like people had started from a flawed feeling, and gotten hold of the statistics and asked no critical questions whatsoever about why the numbers where similar in the poorer areas and similar for social housing.
It's appealing story because it "explains" the high house prices people have to deal with by blaming it on some undefined evil absentee investor which won't show up to defend themselves.
I'll note that I've not looked at the issues related to Paris etc.; maybe it's different there and they have a genuine issue, but even if these numbers were abnormally high, "solving" that problem would not in any case be enough to drive the house prices down to affordable levels - no matter what it's clear that if governments want these prices down to affordable levels, they either have to resort to regulation or to stimulate housebuilding, whether by easing regulations or pouring money into it. But it's much easier to blame people for leaving properties empty.