I agree that they were highly motivated but the notion that they were given the best weapons and even armor is ridiculous. Casualties in penal battalions were 3-6 times higher than in regular units, why would you give the best weapons to soldiers who had a life expectancy of 1-2 months at most?
There is a fail in your logic. It depends what their tasks were. Casualty rates might have no correlation to the kind of equipment a unit receives though it is most likely they are positively correlated (the units who are exposed to combat, particularly high risk combat, receive good equipment). There are very many examples of this:
- U-boats were constantly being updated redesigned. Yet there is no single service in WWII that suffered a greater attrition rate (90%).
- US bomber never expected to finish their 25 mission tour of duty despite flying the most advanced combat systems of their time.
- Casualty rates of Airborne units was expected to be 50% or greater in practically EVERY drop.
Invariably history seems to want to tarnish the commanders as being inhumane when this was rarely the case. The legends of WWI were that the officers dined while the troops died. In fact the officers tried many different tactics, many different technologies, and much training to break the deadlocks. The British officer corps suffered greater casualties than the troops did.
The most inhumane acts inflicted on troops was sending poorly trained troops to the lines. Both sides were guilty. The US sent non-armor trained troops to fight in Shermans (which is the real reason for high Sherman losses, not the equipment) and filled ranks depleted by casualties while units were on the front instead of replacing frontline units to re-train and integrate replacements. The Nazis sent up pilots with only 10 hours of flight time to man high performance fighters.