They. Are. Designed. With. That. In. mind.
They are capable of operation even if they lose trucks (or don't build them)
A major part of the game is decisions, one of the ones okw makes is when to get their medics.. They do not lack medics, they simply need to chose to get them and should they delay it there are plenty of options in place to offset that choice, some commanders like firestorm allow you to even bypass they tech entirely if you so please.
Choices are what make the game interesting and okw economic trade offs are no different.
It IS stark contrast to say the brits whom for some reason the balance team felt the need to waste valuable time to add multiple new healing options despite already having the easiest to access, cheapest and most effecient form, but that's beside the point at hand. Okw HAS healing options, self heal needs to be unturned on volks and things will be a lot more organic. Plus it'll help volks. Win win
As you say its not base on medic.
But you should get medic in either strategy. medic is not part of strategy. its core element of the game.
You need to do macro and blob your unit for medic, and in mid game you need spend lot of fuel for only medic. so its not ok. I say again, I know with tier 2, you can get MG and support gun.
I saying about medic, not other unit. if they add option to get only medic ( no unit - maybe ugrade to get it ) its be more balanced.
The Halftrack had healing before the bunker could have multiple upgrades.
You forgot feuersturm doctrines ambulance truck, which also gets nearby infantry a performance boost (iirc). Also; vet. 4 volksgren have auto healing, which no other mainline infantry has.
I listed all without commander, if i want to put commander i should consider half track for brit or usf