That manufacturing also appears to carry a considerable investment (or possible payoff). One initially wonders why, when manufactured pop stars spectacularly flame out, that they are simply told to go low profile for a while then come back and act like nothing happened...until you think of them as a multi-million dollar entertainment machine their managers no doubt poured tons of money into in the form of singing lessons, dancing lessons, acting lessons, language lessons, etc. plus the money spent on building up "brand" awareness etc.
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.