politics has patterns, it has some procedural and bureaucratic parts, those are very visible (legibility! see also "Seeing like a state")
but in general there's the separation of powers (branches of government), the opposition parties, the checks and balances, and the media.
to answer your question directly, the bigger the government the more separate agencies it has, the more people you need to watch them, the more people are needed to simply raise their voices, give their faces as the opposition, and then more people to keep track of what-the-hell are they doing.
that's how you got special interest groups. single issue parties. (and if such a party manages to raise the salience of their issue to the "national level" then this basically forces other parties and actors to reveal their preference regarding that issue.)
but in general there's the separation of powers (branches of government), the opposition parties, the checks and balances, and the media.
to answer your question directly, the bigger the government the more separate agencies it has, the more people you need to watch them, the more people are needed to simply raise their voices, give their faces as the opposition, and then more people to keep track of what-the-hell are they doing.
that's how you got special interest groups. single issue parties. (and if such a party manages to raise the salience of their issue to the "national level" then this basically forces other parties and actors to reveal their preference regarding that issue.)