THE US ARMY DID NOT WANT SELF PROPELLED GUNSActually they did: the M-3 Gun Motor Carriage (half track), and M-7 105-mm howitzer motor carriage, and the M-12 and M-40 155-mm gun motor carriages, for example. There are plenty of other types to pick from. And they were used like other nations used self propelled guns on occasion.But, this discussion refers to the well armored self propelled guns designed for tank fighting and close support, as used by the Germans and Soviets, such as the STUG and Jagdpanther and SU-76 and SU-85 and SU-100. The US Army did not want combat vehicles without turrets. Some were designed, such as the super-assault gun T-95 with a 105-mm gun. But the US army did not want them.For one thing, they preferred mobility and overall usefulness. And a turret that offered wide traverse. Thus, the only self propelled guns they took for use were intended for artillery use or (as in the case of the 75-mm armed M-3 Half Track) as an interim vehicle until a better replacement was found.The British fielded only one combat-oriented self propelled gun in numbers - the 17-pounder equipped Archer. They too preferred turreted vehicles, many of them acquired from the USA through Lend Lease. They did manufacture SP artillery, including the Bishop and acquired Canadian-made 25-pounder armed Sextons.So why did the Soviets and Germans design and field so many? They were cheap. The Germans were desperate for armored fighting vehicles and built up thousands of turretless weapons using everything from obsolete tank hulls to ready-made hulls to try to fill the gap. Likewise they tried to win the war with technology and hence created some monster SPGs, armed with 88s and sometimes 128-mm guns. If a tank hull could mount a 75-mm gun, the same hull designed into a simple self propelled gun could mount an 88, for example. But the Germans were overwhelmed. So much for technology!The Soviets took the brunt of German panzer attacks and were on the defense much of the time. So, they too wanted to field every armored vehicle they could and hence made heavy use of SPs.After the war, the Soviets continued building SPs, but in the end the tank and turret won out.