The manufacture of the MG34 is immensely complex, yet the Germans were just damn good at curtailing costs. The MG34 wasn't nearly as reliable as a BAR or a BREN, but it's flexibility ran circles around our squad autos so much that it took essentially 3 guns for the Allies to do what one gun did for the Germans. When you get to "total cost of ownership", that's a MASSIVE savings in money. We would have been wise to just drop the BAR, STEN, M1919/1917 Brownings and just flat out copy the '34 and eventually the '42.
Look at the costs
MG34 - $131.00
MG42 - $100.00
Now either of those LMG's could be a squad auto, fixed MG, or Anti-aircraft MG. And they both weighed just a little more than a BAR or BREN and a LOT less than the Brownings
BAR - $319 (over triple the cost of a MG42)
BREN - $180 (just more evidence that the BREN was better than the BAR)
M1919A4 - $579