I'll buy that this is a true native macOS app, but why does it seem to be trying so hard not to be? Why does everything have a flat white background, and why is

I'll buy that this is a true native macOS app, but why does it seem to be trying so hard not to be? Why does everything have a flat white background, and why is the list of data not a standard Cocoa list view? It's still a bit too visually disruptive for my taste.