Yes that is true. In our Civ 3 mod SOE we solved that by adjusting special production levels for each civ in each region of the map. I named that "microzones".
And it´s unbelievable, that FIRAXIS cripples the scenarios delivered with BTS by cutting out all important unique units of these scenarios which give these scenarios their special flavour. This is really no good service for the customers.
One WW2 scenario in Civ 4 vanilla with this complete wrong attitude should have been enough.
No unique units got axed, only the graphics for them. There's 146 units in RtW, 96 of them unique units. RtW is in no way light on UU's.
As for the economy, RtW manages the economy through the use of factories and resources (a new concept to manage what can be built, where, and for how much). You must have specific resources AND buildings to build different units. For instance, to build tanks you must have iron and a vehicle factory. And to build a factory you need power. A barracks gives experience bonuses.
During conquest of a city it is decimated of buildings, so newly acquired cities will take a while to get back to any decent level of unit building speed.
Also, there is a new air mission which specifically targets factories. Your military production can be crippled by successful enemy bombing of your factories. Anti-air units are cheap air defense units for cities to defend against incoming bombers.
Through the use of civics non-fascist industry is regulated. As you research industrial techs new industrial civics open up to you. These civics give increasing bonuses to production and military buildup. This accurately simulates the Allies industrial change from a domestic to war footing. Fascists start with a really good industry as they were already producing on a war footing.
I feel this is a very deep and accurate method to depict the change of industry. It's certainly deeper and more accurate in complexity than any other WW2 mod I've played for any civ version.
Ultimately, RtW is simply a race. The fascists have to race to destroy the allies industry before they can ramp up to out-produce the fascists. That was the key in the 40's, and it's the key in this game.