To answer your question: The reasons why we don't use the same equipment are many, including size, cost and esthetic considerations, but more importantly, what the studio and producer consider perfect is often at odds with the hearing preferences of the end user who may choose to tailor the sound with digital frequency adjustments or simple tone controls as well as their choice of either solid state, vacuum tube or class D amplification.
Humans have very specific tastes in everything, so it's hard for me to believe that this wouldn't have occurred to you.