Axis and Allied tanks operate under different rules due to penetration and armor values with Axis tanks having better armor and Allied tanks having better guns to provide a unique balance to the vehicle game.
When you're looking at a P4J. rough estimate of penetration values probably land around 75% with various differences based on distances and what's shooting, etc. So in your average engagement the P4J can eat 4 shots, bounce one, and die to the 5th giving it effectively 5 shots of health with the scaling rng based on previous factors notwithstanding. This justifies it's increased cost.
The T-34/85 is meant to be an allied version of the P4J mechanically but it obviously can't function as an armored powerhouse due to penetration differences between factions. So it's mechanical function to give it an addition shot like the bounce chance of a P4J is to provide it with 5 shots of health.
This also functions as a way to provide differing balance decisions to vehicles since the T-34/85 having more health means when it's damaged it returns to the field slower since it takes longer to repair. it's weak armor means it's susceptible to weaker sources of damage unlike the less health but stronger armored P4 and as a benefit, it's more consistent of a unit which as a P4J might shake off multiple shots and bully an opposing tank, or just eat 4 shots and die. The T-34/85 will take damage with little to no chance of ever shrugging off a shot. The price of this unit when compared to units of it's equal is fairly balanced by design.
Thx for the detailed answer. I still think the 85 needs to be more expensive (at least 140 fuel) but I enjoy the discussion and you made some really good points.