I largely agree with you on that.
But, that depends on who is using the numbers. For immediate military use it is not important what happens after the war. For the general who is planning a war strategy, what matters is how much the army is losing manpower. For the society it does matter whether the lost manpower is dead or just missing one arm, but for the war strategy it doesn't.
Albeit, I do somewhat disagree with this myself. I keep arguing that although the total military losses of Ukraine are close to those of the Russia, it makes a huge difference that the number of dead soldiers is smaller even in proportion to Ukraine's population than the number of dead Russian soldiers is in proportion to the Russia's population. It also seems that Ukraine's recruitment capacity (in absolute numbers) is at least on par with that of the Russia and it's unclear if its maximum capacity has even been reached.
Ukrainian soldiers seem to always receive decent prosthetics that enable them to remain in working life and be with their families. In that case it is not a huge loss for the society that a soldier has got seriously wounded. If the risk of death was as high as that of Russians', there would be (even) less motivation to enlist.
But, be it like this or that, the reality is that the common practice in wars is to assume it makes no difference whether the lost soldier is dead or crippled, and because of that, they typically count military losses, not military deaths. Regardless of how retarded that is.
Most of them have enlisted out of their own free will. There are plenty of prisoners as well, but – at least to my understanding – they amount less than the people who enlisted for the money. Also, many of the enlisted prisoners are in it voluntarily because of money and amnesty. And many are simply forced to sign the "voluntary" contract by torturing them until they do.
What I've been surprised with is that as long as you are alive, you almost always do receive your salary as a Russian soldier. And your relatives will indeed receive their compensation – assuming there's evidence of you dying. There almost never is, and then you're marked as AWOL, not as dead. And if you're AWOL, your family receives no compensation. Ukraine has huge refrigerated warehouses full of Russian soldiers waiting to be sent home, because when they eventually reach the Russia, that country will either go bankrupt or has to say "we changed our mind. Although you sent your son to our war for money, we're not actually going to pay", which will seriously destabilise the Russia.
This is indeed also why the Russia's economy is such a very important factor here. There's no way they'll be able to fill the required 30 000 new soldiers per month with prisoners alone. They don't have that many hundred thousands of prisoners available for that. Send too many and you will have prison revolts.