In Ireland we compel all state-employees (teachers, police, judges) to be 'fluent' in Irish, so that if someone, wherever they live from Achill to Wexford, needs services in Irish they can be accommodated. This option was briefly entertained in Belgium. But Flemish-speakers generally seemed to be able to retain sufficient French from school to communicate with their neighbours. French OTOH was, from the foundation of the state. the language of The Man and The Establishment often couldn't be bothered to learn the language of the Flemish proles. Does this remind you of Kashmir? ANNyway, the territoriality principal was adopted instead. This said that the official language of each region would be that which was spoken by the majority. You have to petition for services if you are of the minority in your area and if you can muster a quorum - 16 parents can petition for their children to be taught in the language they speak at home. The territoriality principal is full of pride, exclusion and inconvenience . . . although it saves taxpayers money with monoglot roads-signs. We got lost the first time we drove through Belgium because we didn't recognise that Anvers, which was all that appeared on road-signs in Wallonia, was the same as Antwerpen where we were headed.
100 years after the establishment of Belgium, the government felt the need to firm up the linguistic border that cut the country in half like a weeping sore. In 1932, the 1930 census data for all the municipalities along the lingoborder were consulted on the question "What language do you speak at home?" with allowable answers Français, Vlaams or Deutsch. The people in Voeren spoke Limburgish which was Vlaams in the sense that Frisian is Dutch: i.e. not very much. But given only three choices, and allowing for self-declaration, the data came out clearly in favour of "Vlaams" being the dominant language in the area.
But we can all agree that Belgians, whatever they speak, make the best fries.