Getting precise shape of license plate

Hello,
I would like to know whether there is a difference between Open-Source & Commercial versions regarding quality of "focus"on the license plate shape.
Trying to use the On-premise Open-Source version to recognize European plates (that have 3 areas inside : LEFT for the country identification / CENTER for the plate number itself / RIGHT for the region), I got unstable results as the coordinates include not always the same areas of the plates.
Sometimes I got all 3 areas, sometimes it is only the left and center areas, sometimes the center and right areas. Up to now, I never got only the center area alone…
Nevertheless, it is key for me to rely on precise shape of the plate as I want to use this information to determine the distance to the vehicle.
Are you able to recommend me the best solution?
(I have been trying setDefaultRegion(“de”), but do not think this matters so much…)
Thanks in advance for your reply