Sondheim shows get a rap for not always turning a profit initially. And, as Margo has pointed out, it is not always true.
Look at the long LONG list of stagings of his shows in the back of TSR magazine. Each one of those pays a fee to put on that production and that income can often push a (financial) flop into the hit category.
You want to hear somethng even more troubling: Of all the shows Kander and Ebb wrote, only 2 (CHICAGO and CABARET) ever paid off. (Twice if you count the revivals!)
FLORA THE RED MENACE, THE HAPPY TIME, ZORBA, 70 GIRLS 70, THE ACT, WOMAN OF THE YEAR, THE RINK, KISS OF THE SPIDER WOMAN, and STEEL PIER all lost money!
As for ALW - his flops include: WOMAN IN WHITE, BY JEEVES, SUNSET BLVD, ASPECTS OF LOVE, STARLIGHT EXPRESS, SONG AND DANCE and the revivals of JOSEPH (1993), and JESUS CHRIST SUPERSTAR (2000). Of course his big hits (CATS, PHANTOM) have come to define Brodway for some people.
And as for Frank Wildhorn...NONE of his shows has ever even come close to breaking even.
Public perception is different: A show that ran a year or more, toured, had several regional stagings and community theatre productions is percieved as a hit (even if the original Broadway staging lost money.)
And a funny thing: sometimes people assume a short runs means the show played at a loss. PETER PAN (1954) was only scheduled for a limited run of 19 weeks since a deal had been made in advance to show it live on NBC in March 1955. Though the run was only 152 performance it was a financial success. The Angela Lansbury GYPSY was only scheduled for a 120 performance lmited engagement at the Winter Garden in 1974 as part of a North American tour, and that production also was a success.
And no one (except maybe the investors) really cares. I have yet to hear someone refuse to go see a production of RAGTIME, DROOD or CANDIDE simply because it was a (financial) flop on Broadway!
Cast albums are NOT "soundtracks."
Live theatre does not use a "soundtrack." If it did, it wouldn't be live theatre!
I host a weekly one-hour radio program featuring cast album selections as well as songs by cabaret, jazz and theatre artists. The program, FRONT ROW CENTRE is heard Sundays 9 to 10 am and also Saturdays from 8 to 9 am (eastern times) on www.proudfm.com