The reality of it is that "enhanced" performances are a standard part of the music entertainment business, from guys like us using SMFs or even styles, to top 'pop' stars, to Broadway musicals, and on and on ... while the the Jazz, Classical, and most Folk music performers are still playing what you are hearing, many - dare I say most? - other acts have some programmed material ... now this can be due to many reasons, but I think it is mostly economics ... it is a lot less expensive to have a sequenced string section than it is to hire one ... at a recent local musical play production the 'orchestra pit' consisted of a bass player, a drummer and 3 digital keyboards playing all the string, horn and other parts ... In the video you can see the father standing behind a keyboard - singing, but not playing ... now he could have stood anywhere on stage, but at least he isn't pretending to play the KB ... apparently they are comfortable with what they do ...
I think 'TBW' gig in Vegas is from September through December, as their calendar shows them in Florida in January ... but good for them ... they found their nitch, are good at it and are entertaining a LOT of people ...