Small countries have small elites that are far more likely to have gone through the same educational institutions and run in the same social circles. A corruption of back-scratching at the top, where consequences and laws are for the little people, rather than a culture of pervasive bribery.

Ireland is corrupt like this - not for major crimes, just lots of little things, like planning permission and speeding points on driving licenses.

Nobody wants to make a big stink because everybody swims in the same small pond, and what goes around comes around.

Here's a case study on the topic of speeding points: https://www.theguardian.com/media/greenslade/2013/oct/03/iri... ; speeding points corruption is an ongoing political issue that has brought down multiple justice ministers, primarily due to the attempted coverups (trying to silence Maurice McCabe).