Why? It shouldn't be. They use 3-phase in Europe just like in the US, for industrial locations. The differences in residential or lower-voltage standards really have nothing to do with industrial power availability.
The author described some shenanigans he had to go through when wiring the power cord to get the power supplies (which expected voltage that is typical in the US) to run right. In the US it would have been a simple matter of using a power cord in the standard configuration and plugging it into the wall.
Looking closely at the photo of the power supply in the article, it looks like it's quite flexible and can handle different voltages, as long as they're 3-phase. It even lists different amp draws for the different voltage levels. In addition, it looks like it can handle 380-570V DC. With today's switching power supply technology, it's not hard to make them able to accept widely differing input voltages, so this is commonly done so you only need one part to cover the entire worldwide market. It looks to me like you can just plug this thing into any 3-phase power you want really.
As for a "standard configuration" in the US, there really isn't such a thing for 3-phase power. There are a few NEMA standards used in industrial applications, but a lot of times, things like that are hard-wired. This isn't a home appliance.
