I've driven in a lot of countries.
IMO, Belgian drivers aren't very good (but then again, IMO there are few drivers in
any country who've merely done the basic driving test who are anywhere near 'competent'.)
Driving instruction - although it should be 'harmonised'
does vary markedly from country to country. There are one or two EU countries (no names, no pack drill) where the standards of driver training and driving are abysmal!
Should you live in a country where driver training standards are good and where drivers are a little better than the EU average, don't be lulled into a false sense of security. Anybody with a valid EU licence can drive anywhere in the EU - and they do, too!
A previous poster talked about 'lane discipline'. LOL!

There is one place where I declined to drive. Sicily. (I've nothing against Sicilians; they are quire amazing drivers) - and I did learn a few of the 'local' rules:
1. The number of lanes marked on the road is a suggestion. If there are 3 lanes, but you could get 5 vehicles abreast, do so.
2.
Right of precedence (really important rule) When vehicles are stationary at traffic lights (or any other impediment to free flow) the vehicle (on either side) which has its front wheel nearer the holdup than any other vehicle has absolute right of way... So when you are approaching a red light, go like hell, scare the hell out of the opposition and get Pole position.
3. The footpath is for Fiat 500s (the pedestrians will get out ofthe way) - Beware joining traffic (small cars) from the footpath.
I refused to drive in Sicily; I 'allowed' my navigator (who was as blind as a bat) to drive. - he couldn't see, so he didn't get scared.
Driving standards in Belgium could be better - and the insurance premiums do tend to reflect that (mine dropped by over 1000 Euros when we moved to Germany.)
There are advantages, however. I was in Paris (a city not exactly noted for gentlemanly driving) a few years ago. I was, however, in a Belgian registered car. I just pointed the car and put my foot on the pedal ... for some strange reason, the Parisians were remarkably willing to cede to me 'right of way'.
Funny old thing.
Serious advice - for foreigners and for people who simply wantto stay alive: If you can find a company (or a charitable organisation - there are many in the UK) which offers advanced driver training, do the course.
I've done loads of courses (if anybody offers me a driving course, I'll take the offer) and although some of them are a 'pain in the butt' I learn a it from every course.
Some of the courses I've taken have reduced m insurance premiums (by up to 20%). They
all increase my chance of survival.