Even Austria-Hungary had a tiered structure for minorities; the Hungarians were practically on par with the Austrians themselves, and together they dominated the rest. Austria itself was so involved because when the two most powerful German states battled to head all of them, Prussia won and Austria had to seek power elsewhere.
Bismarck handled that masterfully.
He knew it’d take a war to get Austria out of German affairs, but he made a generous peace with them so that they’d be allies.
If only he’d done the same with France, and not taken Alsace-Lorraine!
And later, if Germany had not tried to compete with Britain over naval armaments, we might have avoided WW1.