Ukrainian puzzles and numbers

A puzzled observation in two parts, magnitudes and sophistication.  

Watching developments in the Ukraine I see two different things happening, both of which I find hard to explain or understand.  Just to be clear, I am delighted that the Ukrainians have been able to sustain themselves and demonstrate success under exceptionally difficult circumstances.  My puzzlement is about integrating different knowledge sets.  

Ukraine is a geographical area which, in World War II, saw the clash of Soviet and German armies on an astonishing scale.  Examples

Battle of Kiev - August and September, 1941.  The Germans had 550,000 troops and the Soviets, initially, 630,000.  The Germans lost 61,000 in casualties and the Soviets 700,000 (including captured).

Battle of the Dnieper - August to December, 1943.  The Germans had 1,104,000 troops and the Soviets had 2,633,000.  The Germans lost 372,000 in casualties and the Soviets 2,900,000.

Second Battle of Kharkov - May 1942.  The Germans had 350,000 troops and the Soviets had 765,000.  The Germans lost 30,000 in casualties and the Soviets 277,000.

Third Battle of Kharkov - February and March, 1943.  The Germans had 70,000 troops and the Soviets had 210,000.  The Germans lost 11,500 in casualties and the Soviets 86,000.

Now compare to the current war arising from the Russian invasion of Ukraine.  The troop levels and losses are extremely rough estimates.  Probably accurate only to an order of magnitude.  

Battle of Kyiv, 2022 - February through April 2022.  The Russians had 30,000 troops and the Ukrainians perhaps 35,000.  The Russians lost perhaps 5-10,000 and the Ukrainians about 1,000.  

Siege of Mariupol, 2022 - February to May, 2022.  The Russians had 15,000 troops and the Ukrainians perhaps 5,000.  The Russians lost perhaps 6,000 and the Ukrainians about 4,500.  

In both wars, these battles, and the general battle for Ukraine were strategic for the German (and later Russian) war goals and existential for the Soviets (and later the Ukrainians).  

Yet the size of forces deployed today, and corresponding casualties suffered, are but 5-10% of those in World War II.  Why?  Why were the forces so much larger then when the stakes seem roughly comparable.  Why are the casualties so much lower now?

I sort of see part of the answer.  The battles for Ukraine in the second world war came three years after Germany's mobilization.  They were ramped up.  Taking this line of thinking, there is no real way to compare battles in an area that were three years into a six year World War versus an elective or discretionary war (for Russia) which stands alone, is not part of a larger ongoing combat, and is only seven months old at this point.

Still, the differences in magnitude are simply astonishing.

As of today, it appears that the battle for Lyman, Ukraine may be over and that the Ukrainian forces have retaken it and either captured or killed its 5,000 Russian garrison after four weeks of campaign.  Lyman is a strategic logistics town whose possession is likely to significantly affect the prosecution of the war to the detriment of the Russians.  We don't know the size of the forces involved or losses for either side yet but it seems like we are talking about less than 40,000 deployed in total and perhaps 10,000 in losses (probably heavily weighted on the Russian side.)

So a puzzlement about respective scale across the eight decades is one of the observations.

Sophistication is the ambiguous second observation that might also be part of the explanation for the first observation.

The HIMARS systems, the respective air forces (such as they are), the tanks, the communications and signals sophistication, the command and control structures (at least for the Ukrainians), the logistical sophistication (again, at least for the Ukrainians), the drones, the anti-tank guns, etc.  All are orders of magnitude more complex, sophisticated, and effective than anything in World War II.  It is almost possible to imagine a modern equipped Ukrainian army of 200,000 taking on the 3,000,000 experienced German army equipped as it then was and winning.  

Is this equipment and war-making capacity today in part why the troop numbers are so much lower than those in World War II?  Has our technology of war-making made us so much more efficient that the human numbers can be lower?  

And are the numbers so much lower because the cost of that equipment is so much higher than the category comparable in World War II?  A single Russian T-90, and certainly its category peer, the Abrams, today could likely take out an entire WWII German tank battalion of Tiger IIs (roughly 40 tanks).  Today's Abrams might be able to singlehandedly take on and defeat an entire armored division from World War II (about 260 tanks).  

An American Sherman tank in World War II cost, in today's currency, perhaps $700,000.  Today's Abrams tank is about $9 million in today's currency.  In constant dollars, an Abrams tank is maybe thirteen times as expensive as a Sherman but probably 30-50 times as lethal (don't go down the Reddit and Quora rabbit holes.)

Interestingly, the Soviet population in 1930 was some 170 million whereas today's Russian population is 144 million.  Roughly comparable in size, but in the existential struggle of World War II, the Soviets were able to muster and deploy an army of some 11 million.  Today, their entire military and economy is hostage to a conflict of nominally some 190,000.  

So I wonder if the cost and sophistication of war is simply making it prohibitive to deploy the types of armies which we once did.  Perhaps the relative weapon lethality is now so much greater than in the past that it constrains where, how, and under what circumstances it can be deployed, thereby constraining the lives lost?

I simply don't know but the numbers are a puzzle.