Lol, I love how you question if I've live/d there, like the complete inability to take in information that might not be fit to your world view.
This is clearly not true in general.
The French term commonly used in the media is "zones de non droit" meaning "areas outside of the law" or sometimes, perhaps more politically charged, "territoire perdus de la république" (the republic's lost territories).
Officially they are known under various names that start with "zone". Currently the official term is "zones de sécurité prioritaire" (areas of priority security).
Those areas generally correspond to the areas that most countries warn about in their advice to travelers when it comes to France.
They exist in other European countries as well under similar names.
So, I assume a lot of propaganda around that?
I don't think it's political. I think some people have just grown up in very safe environments and have a smaller comfort zone.
Of course if you're intimately familiar with this by living in France or something I wouldn't question it, but if you're just looking in from the outside, then it's all shadows on a cave wall.
Using footage from demonstrations that got out of hand, civil unrest at one point and overblown as well as wrongly cited numbers are all that is to that.
And yes, in Europe there is no such thing as no-go zone where police don't go and all you have is anarchy.
https://www.elysee.fr/emmanuel-macron/2020/02/18/proteger-le...
He is using multiple times the expression "quartiers de reconquête républicaine" ("suburbs for the Republic to re-conquer").
If the President of a country considers he needs to reconquer parts of his own country, don't you think there is a bit of a problem, beyond whatever Fox News might say?
You might think there is some nuance because the areas with risk of Islamic separatism are not _necessarily_ the same as the high-crime areas where the police cannot easily go. But in practice they definitely are. It's not a pleasant situation, but it's the situation.
I can give more background if you are interested, but it is a well-studied problem with no solution in sight.