It is easy to dismiss PG's entire article -- from its foundation to conclusions about transparency -- if you've already concluded that democracy does not exist; that votes do not translate to power in any meaningful way; that capitalism has become the real foundation on which political power is merely a simulacrum. In doing this we've hit philosophical bedrock with the shovel of pessimism, and the discussion ceases to be productive.
The law only codifies what the people, through their votes, decide to codify within it. Capitalism does not a priori codify wealth as political power. The law merely aids the confluence of capitalism: money, a signifier -- to represent resources: the signified. Capitalism is contained within the theater of democratically held political power -- until it corrupts that containment. PG's mention of secrecy in a democracy is a useful one: secrecy subverts the power of the informed voter, it is a breach of that containment. It allows the potential for capital to slip out into the realm of realpolitik -- which is reserved for the people alone through their vote.
I think if you review what PG is saying about corruption through the prism of philosophy without the distortions of politics itself (and all its frustrations) you might not consider it unsubstantiated idealism or what have you.
> It's a matter of degree.
It has nothing to do with "degree". "Corruption" has nothing to do with the mixture of wealth and power: in extremely capitalist societies the Law codifies wealth as power (eg. Citizens United) and in extremely Socialist societies it codifies the opposite. "Corruption" is perceived to be prevalent in societies (eg. italy) in which the public and private sphere are blended and the Law tracks this lack of clarity.
This is why its not sufficient to say "abuse of wealth" is corruption and we need to fix corruption. Because "corruption" is defined by and against the norms of particular societies and does not measure how much wealth distorts the political landscape. Americans do not see owning many news outlets as "corruption" for example, but it is arguably an abuse of wealth to gain political power and influence.
To treat his articles seriously and engage with them (I have written about his essay on Philosophy before) is to give them too much credit. If i wanted to contribute substantively to this debate I would go and find someone informed on the matter and reply to a essay they have written. To reply to pg is to educate him.