Re: no one is being forced to join the Euro
And because Belgium is chaotic neutral, that "regional" government has legislative equality with all the other governments. All seven of them, federal and three regional, three community.
So it's not like Bavaria or Scotland blocked it (their legislatures are subordinate to the union they belong to, Germany and the UK in these cases), but that Belgium has seven equal parliaments, and thus each of those effectively gets to exercise Belgium's veto power without, uh, veto from the others.
It is bonkers, but that's more because Belgium is nuts. Lovely country to visit :D