Sound stage of studio recordings

this somewhat depends on the era of the recording. and the musical genre.

prior to the mid 60's most studio recording processes were more simple, and it's more likely that performers are where the recording places them, and that minimal or no manipulation is done. going forward from then, most jazz or small combo classical continues to be recorded more simply, with minimal manipulation. but studio pop is almost always assembled from multi track recording processes.....so any result is possible. or it's recorded in someone's basement from pieces recorded at different times.

hifi systems also have a contribution to the degree of imaging and the perception of the sound coming directly from the speakers. non musical distortion locates the sound directly from the driver, as opposed to the music which is located in the soundfield.

@cleeds 

I really like simple trios, quartets. When you go to a live show and the piano is here, the bass is five feet to the left and the drums are in the middle. But like you said, when they mike every cymbal and drum, the mix usually has the drum kit appearing  to be as wide as the stage. Or if they use several mikes or a stereo mike on the piano, it’s the same thing.  The piano sounds like it’s as wide as the stage.

The decisions of the recording engineer and producer determine how the soundstage is reproduced.  That is why you state that “on some recordings it is hit or miss”.  Decisions on the venue, microphone placement, recording equipment, phasing, and mixing all impact soundstage reproduction.  IMHO, and realize I am speaking in broad generalities, single or minimally miked recordings from companies like Linn, Wilson, Stockfish, Maple Shade, Chesky, Reference Recordings, Naxos, Proprius, Etc. produce naturally wide and deep staging.  The old multi miked recordings from RCA, Decca, and Mercury from the 50s and 60s also produce excellent staging where engineering decisions such as close miking a drum kit or a piano in the middle of the sound board are also evident.  Offerings from 2L are multi miked with excellent results as well.  Most modern pop is studio produced with isolation booths.  Mixing determines soundstage placement.  A vocal can be dead center or off center.  When you hear instruments around you (think Waters, Amused to Death) is usually a decision to record out of phase.  Therefore, the differences you hear are the artistic decisions of the recording engineer and producer, with input from the performer. I have attached a good review article.  
 

The hype (which I guess I buy into) about the (DDD) recordings of The Cowboy Junkies Whites Off Earth Now and then The Trinity Sessions was all about the great job that was done of single miking them.

The simple answer is that mixing boards have pan pots. You mic something and the panning allows you to place it wherever you want in the stereo image. Live mixing keeps everything mostly in mono so the audience all hears the same thing. When doing live concert mixing I often put a small amount of stereo reverb in the mix to fool people into thinking they're having more fun than they actually are, and a recorded feed from the board can be multi tracked to mix it later.