Let's take the US as we know it, the 1780s constitution granted the Federal government power over interstate commerce, like a glue between the states, by the 20th century all commerce was interstate commerce and the "New Deal" in 1930 leveraged that to assume control over all facets of life in the US, with the Supreme Court finalizing the subjugation of all the states shortly thereafter (for example with rulings that a farmer's crop in one state affects the national market of that crop and therefore can be regulated by the federal government). All autonomy of states is merely tolerated by the Federal Government to maintain easier compliance. A pacifier in the mouth of a dependent which could realistically be removed at any time.