How do Germans get that deep color and waxy finish on their Easter eggs?

They use natural dyes made from plants. A chart can be found at this link. Naturally-dyed eggs have a lovely matte finish reminiscent of old milk paint, but eggs can also be oiled to a satin shiny finish. After eggs have dried, rub them with an edible vegetable oil such as canola oil or olive oil using a paper towel. Wipe with a dry paper towel and buff lightly.

the traditional dyed eggs are boiled with colouring & once cooled, rubbed with a cloth thats been dipped in a little olive oil, then again till the polish is done.