Trading Places has two different serial plots portrayed through the film, the first of which being Louis trying to regain the lifestyle he had lost to Billy Ray through the wager proposed by the opposing stance of the estately Duke Brothers on the argument of "nature v. nurture"; and the second turn of events in the story evolved when both Louis and Billy Ray concocted their mutual scheme to bankrupt the wealthy yet snobbish Duke Brothers.
The second sequence of the film when this plan of action is set in motion is what I consider a classic "caper". Two savvy antagonists band together in a communal compromise to gain riches and also shaft their original wrongdoers for the misdeeds played upon them. That's a good enough synopsis for most of the countless other "caper"-themed films I've watched through the years. And for that reason, that is why I consider
Trading Places a good fit in this realm of comedic heist films.