>They are rude, they will deny everything, if you try to escalate they threaten you (even if you show them evidences and no matter how well you documented things)

From my experience as an immigrant, it's exactly the same in Germany and Austria. For the locals who grew up into the system it doesn't feel terrible, but if you grew up in a country with common sense in business, this is infuriating.

>I think this extra 'arrogance tax' makes people think it twice before doing business in Belgium.

I think this is an intentional feature, not a bug. It's a hidden form of protectionism against EU's freedom of movement and trade, to discourage foreigners or small businesses from chapter countries with hustle mentality, to come in and displace entrenched local businesses who would like to have their cake and eat it too, since this pattern appears way too often in EUs rich countries to be just a coincidence. They specifically DON'T WANT YOUR business be opened there because then you're a competitor to the business establishment status quo there, but they can't outright say that.

Here is my take (spoiler: I disagree a bit)

I observed is that Belgian people apply the same bad treatment to other Belgian people. So I believe this has nothing to do with racism or protectionism.

The culture is simply like this, and they are both victims and perpetrators of their own behavior.

In a way, that makes me be a bit forgiving, but still, it is sad to see this unconstructive and toxic behavior.