They might be (no idea), but if they are there's a significant amount of leeway allowed and visible between municipal roads in Bavaria and Brandenburg (richer vs. poorer states...)

Edit: no, at least part of them is state specific, e.g. Saxony road administration law: https://www.revosax.sachsen.de/vorschrift/4785-Saechsisches-...

Oh interesting! I'm honestly surprised because roads always seemed so much more consistent to me in Germany.

Also, "Bepflanzung des Straßenkörpers" might be the most German thing I've read in ages ;)