Article 19 of the First Geneva Convention covers all medical units, not just the Red Cross. It is just as illegal to target an enemy medic as it is to target a Red Cross medic. Both are war crimes.
Was anybody prosecuted by the infamous 2007 attack to an ambulance in Baghdad shown by Wikileaks, (oh, yes... Manning of course. Silly me. I almost forgot)
Was anybody jailed for the men and woman and children burnt alive by the "strictly forbidden under international laws" white phosphorus in Fallujah? noope
Were the systematic bombing of hospitals and civil buildings in Gaza, Pakistan or Syria investigated?
Was somebody prosecuted by what they did to Omran Daqneesh and his family?.
Or by the annexation of Crimea?
I could spent the next hour enumerating cases of war crimes written in flashing neon letters, solved with a path in the shoulder to the criminals. Is a fact that war crimes go often unpunished when commit by "the good guys".