in US it's all about LIVE.OK 3 piece combos bands will fill any bar than top arranger giggers.
also the major popularity is AMERICAN
music,country to jazz and blues,audience expects sax player/or slide gtr etc players.Blues/jazz is a major LIVE music that people expects(in malls,any special occations etc ),not pop.if you are 4 piece band(drums,bass,keys or gtr and a horn player it's easy to find band gigs including weddings etc).

another important fact-full band LIVE BAND music also is relatively easier to do (compare to EU)because the demand and self transportation is relatively easier(gas prices to cheaper cars,do you know that in most EU countries ,1 gal of gas is $7).most band memebers have own transportation so lugging you acoustic kit, tube amp,4 x 10 and 88 keys and PA and driving 40 miles everyday is not a big deal here.