Because corruption as an issue is overrated or wrongly defined. South Korea and Japan are mentioned in the article as exemplary countries when it comes to internet speed and infrastructure but both have virtually no dividing line between private conglomerates (Chaebol and Keiretsu respectively) and public administration. The same is true in Germany, but with few exceptions that kind of intersection doesn't matter because governance is by and large effective, which beats clean.

In fact this kind of conglomeration between the public and private sector is why they get things done, compared to the vetocratic nature of other countries.