From Nathaniel on Patreon:
"Why didn't Germany or Axis powers have a machine gun similar to the American M2?"

Basically, because everyone faced the choice of a .50 caliber machine gun or 20mm (or larger) cannons for anti-aircraft use, and most people chose the cannons - including Germany. There were some .50 caliber machine guns adopted by Axis powers, most notably the Hotchkiss 1930, a magazine-fed 13.2mm gun that was used by both Italy and Japan (among others). However, the use of the .50 caliber M2 by the US was really a logistical holdover form the interwar period. The M2 remained in production because it was adopted by US Coastal Artillery as a water-cooled anti-aircraft gun, and commercial sales by Colt were slim but sufficient to keep the gun in development through the 20s and 30s. It was used as a main armament in early American armor, but obsolete in this role when the war broke out.

However, with the gun in production and no obvious domestic 20mm design, the US chose to simply make an astounding number of M2s and just dump them everywhere, from Jeeps to trucks to halftracks to tanks to self-propelled guns. And that's not considering the 75% of production that went to coaxial and aircraft versions...

Anyway, back to the question. The German choice for antiaircraft use was the 20mm and 37mm Flak systems, and not a ,50 MG on every tank turret. And so, there was really no motive to develop such a gun. The Soviets did choose to go the US route, though, and developed the DShK-38 for the same role as the US M2 - although it was made in only a tiny fraction of the quantity of the M2.

Thanks to Nick Moran (the Chieftain) for his assistance on this video!