I follow Korean pop culture more than Japan's, but I definitely have a sense that the K-POP labels have virtual stables of up and coming "properties", getting paid little, living in bunks with other stars-in-training and eating instant noodles, but being given the very best in song and dance lessons for hours a day, waiting to be selected by their manager to begin a nationwide PR blitz and concert series for at least 2 years of "instant" stardom, then cultural obscurity.
I imagine that something no entirely dissimilar happens in the U.S., but the feeder system is all different...
The K-Pop starlet BoA is one I remember very well (also semi-popular in Japan if I understand correctly), chosen at about 13 (years ago), dropped out of school and "manufactured" through endless training programs to become what she is today. Interestingly, she was an investment by her label specifically for export to the U.S. and Japan. She hasn't done well in the States, but her label seems happy with her performance across the Sea of Japan, infiltrating J-Pop. Her interviews in the States (in very good, but accented English) came across as weird, slightly aloof, uncomfortable and detached...kind of what you'd expect out of somebody who has never really lived a normal life.
Every once in a while the mainstream will flirt with some of the indie groups, sometimes some of the style rubs off and the Pop industry will change.
One very well known case (in Korea) http://en.wikipedia.org/wiki/Seo_Tae_Ji basically revolutionized the entire industry a couple of times, changing styles like some people change hair cuts. He basically introduced hard rock and rap into the mainstream (which basically was stuff like this https://www.youtube.com/watch?v=w2lD9cvkDx8 ) until he came along.
But there's really some great stuff in the indie scene there. One duo has recently started getting noticed a bit in the mainstream.
Someone I knew in London 5 or so years ago got a Development Deal with one of the major labels. He stayed in his normal job, but was paid a retainer to not talk to any other labels for a period of time. I don't know how much it was, but the first time the money hit his account he thought he'd been overpaid and called them so they could correct their error - he was told it was the right amount.
They'd give him some studio time occasionally and have him record demos and do showcase performances for various important people. They offered him a personal chef and a personal trainer to tone up.
Last I heard nothing had ever come of the whole thing. No records released, no attempt at publicly launching his career, etc. I assume the money stopped coming at some point.
Sort of the feeder leagues that produce second and third rate stuff until something percolates up and makes it into the major leagues. I wonder how much music (and videos) is out there? I'd bet some (a small percentage no doubt) of it is pretty good.
I would bet the ad spends and branding costs would dwarf the money spent directly on grooming the performer.
They basically did.
http://www.theonion.com/video/disney-lab-unveils-its-latest-...
Seeing this, I think that could be closer to reality.
If Disney could produce popstars in a laboratory they would.
For folks interested in how the Japanese content industry does it, see Merry White's books on the Japanese youth culture, particularly as it regards magazines. (They might need an update for the Internet age, but not all that much of one.)