The "orchestras" for Broadway musicals have mostly become a joke. And the audiences don't seem to care or to know the difference.
In the past, the pit orchestra would be somewhat large, between 25 and 30 musicians. These ensembles would be made up of woodwinds, brass, percussion and strings. On some shows, there might be a second keyboard player using an electronic keyboards but it wouldn't serve the purpose of replacing live musicians. Over the past several decades, however, that number of players has been chiseled down to less than a dozen.
Producers and theater owners have driven this trend because it lowers the labor costs for their shows. To make the situation worse, on some shows the orchestra, such as it might be, is underneath the stage and the music is mixed by an audio engineer who sends the mix through speaker systems in the auditorium. Consider that the audience isn't hearing "live" music; the music is coming through speakers. In reality, what is the difference between that and Karaoke?
To make matters worse, most audiences today don't really know what real instruments sound like. They don't even know the names of the instruments! Why would they care, then, if there was a real trumpet or violin accompanying the show?
It's a depressing trend.