Just don't overtake at +30 kph but more at 10 kph

The law does account for this: If all lanes are well populated and you find your lane is actually moving faster than the lane to your left, you may pass - not overtake - on the right, as long as you are not more than 20 kph faster than the left lane.

The difference is in passing and overtaking: Passing is merely going faster than the other lane, but staying in your lane afterwards. Overtaking, or to give it its correct name of undertaking, is passing and then changing into the same lane as the passed vehicle.