One of the arguments I heard around corruption caused by lobbying is that centralization of power makes it worse. It kind of boils down to persuading one person is easier than convincing many people.
Maybe in theory but in practice even in less centralized systems there is still generally just one person you need to persuade, and that one person is generally easier to persuade than if they were more central. If you compare local governments to state governments to the federal government, there is substantially more graft in the smaller governments. Local officials are cheaper to influence, have less of a spotlight on them (both from criminal investigators and the electorate), and have fewer competing interests to worry about.