Incorrect comparison- for cost, USF armor is exactly as good as it should be armor / health wise, which is my point. USF doesn't suffer for lack of higher-tiered vehicles in the least (possibly in 3v3 and higher, but I never encountered problems even there while playing USF without EZ8 or Pershing).
You can also not build T4/Tiger as Ostheer and perfectly win a game vs any player. But you have the option.
As OKW, you can win with only Pz4 and Jpz4 (most players do) and not build panther or KT. But you have the option.
As USF, you simply didn't had the option till the commander with Pershing and still it is doctrinal.
Terrible comparison, since ambulance is infinitely more flexible than every other faction's healing (Base medics, medic bunkers, healing tommies, battlegroup HQ). It's also a bad comparison because you still bypass the ambulance until after LT / CPT and the light vehicle, which gives the early game strength that USF has in terms of MP spent on combat units.
More flexible, more wipeable and more expensive, Ostheer Sdfk and Sov M5 are infinitely more flexible (also look at speed stats) to reinforce on the field and dps, it is a matter of preference and the end: heal + reinforce on your territory or reinforce + transport and dps anywhere on the field, but saying the ambulance has no equivalence is a pure lie.
OKW is different but doesn't suffer anything on this point with a free medical truck + mp investment to make it forwarded point.
Seriously? The self-repair of USF tanks is the single best ability to augment the overall combat potential of vehicles in the game. I can't believe any logical player of any mode in COH2 will deny the immense strength of self repair.
Self-repair comes with lower armor power in general: lower armor values and lower pen values. Ostheer, till the recent Sherman buff, had better armors in all aspects. Not to say the Sherman buff has been done to respond the fact it comes around after the Ostheer Pz4. Now it is true Ostheer may lack something in this area.
OKW has a free repair station in addition to a boosted Pz4 and a boosted Panther, with the coming patch both coming at the same time you can field a sherman. Free Repair + better armor + better pen value opposed to self-repair. If it is balance for you, well we've nailed the root of the issue.