I think the differences between the UK's Dragons Den and the US' Shark Tank show some fundamental differences between what British viewers want to see from this type of show, and what Americans want to see.
Dragon's Den seems to revolve around cringe.
Shark Tank, on the other hand, seems to be focused on proving that the American Dream is still alive and well.
I think both the British and the Americans enjoy watching people fail spectacularly. Schadenfreude, and all that. But when it comes to Dragon's Den / Shark Tank, Brits mostly want to see entrepreneurs fail, while Americans mostly want to see entrepreneurs succeed.