Why there is little or no difference in RD between troops in a Halftrack and those in a soft top truck?
Often half-tracks are seen as some sort of super weapon. But 14.5mm of armour in an open-topped vehicle acts more as cover rather than providing all-round protection. When the armoured infantry dismount to fight they leave the relative safety of their vehicles and function more as normal infantry.
In situations where panzergrenadiers fought from their vehicles, they had to expose their heads and arms to fire. Staying in the half-track also removes their ability to spread out (squad dispersion) making them an easier target for enemy fire.
Looking at Half-track stats from a purely mechanical perspective a half-track gains +2RD for medium cover (armour protection), but loses -1RD for being a condensed infantry target/fighting dismounted. Overall it gets +1 RD.
Truck-based infantry have no change to RD. They have the same RD whether mounted or dismounted. However, once dismounted they can go to ground to gain +1RD, but move at Slow speed. Put infantry in trucks and they move faster, but don’t they gain any other benefits.
A half-track improves movement speed, increases Firepower by +1D and also increases Reaction by +1D. As an all-round package it gives an advantage over normal “leg” infantry but not an overpowering one.
Transport infantry in Kangaroos and they benefit from being an Anti-Tank target until they dismount. A Ram Kangaroo gives the infantry 5RD (A-T), but the infantry can’t fight from the kangaroo and are vulnerable to Firepower attacks after dismounting. A kangaroo can get infantry safely to the combat zone, but its really just an armoured bus.
Armoured Personnel Carriers
Following World War Two half-tracks were abandoned by most armies in favour of armoured personnel carriers. APCs provide faster movement, all-round armoured protection, safe firing ports and sealed environments to protect against chemical attacks.
World War Two half-tracks were an essential step on the way to modern APCs, but were a flawed design that failed to fully protect the infantry. I see their speed and supporting weapons as the main advantage of half-tracks. The armour protection helps, but it’s remains an infantry unit, not an armoured unit