The problem is they weren't really "in hiding." The SS was not the only organization responsible for the atrocities in WW2 and the regular German army the Wehrmacht was complicit in almost all the atrocities of the Nazi regime, often working hand in hand with the SS, yet the leaders of the Wehrmacht after the war came away clean and even today the paltry few they are prosecuting are low ranking SS stooges who had no real power or responsibility for the decisions or actions of the military and government.
You have to look up the Himmerod memoradum and the formation of the Bundeswehr to understand why these people haven't been prosecuted until 72+ years after the war, and why almost every major German commander and leader got off virtually scot free.
After the war the German government and the allies agreed to whitewash the actions of the Wehrmacht and most of the SS in exchange for there soldiers forming a new German military to guard against the Soviets. In exchange for forming this military the West agreed to pardon most war criminals, stop prosecuting members of the military, treat the waffle-ss as regular veterans, and to present the myth of a "clean Wehrmacht."
Its only been since the late 90s, coincidentally after all the generals and high ranking officers who made this deal died and the soviets collapsed, that all off a sudden the ''clean Wehrmacht" myth has taken a hit, and the German government started finding these "hiding" Nazis and SS members.
In reality they knew the entire time who these people were and willingly let them live their lives and even gave them veterans benefits and honors in exchange for their commanders help in establishing a bulwark against the Soviets. Once the Soviets collapsed and all of the Wehrmacht higher ups died they are picking off a few dozen of the lowest ranking survivors of the SS in order to make a show like they were always dedicated to searching out and punishing these terrible criminals