The thing is, spec scripts are cheap--if they're purchased and filmed, they make up a tiny portion of the film's budget (with rare exceptions). Stealing a screenplay is a terrible way for a major player to save money. (In my ignorant opinion, "Coming to America" was probably more an issue of vanity than stinginess.) If the supposedly original script was close enough to fhe filmed Holdovers, why not just pay the original writer and hire someone to re-write if necessary? Studios used to pre-emptively buy scripts that were similar to works they already had in development, and then sit on the script, just to avoid a plagiarism suit. (I don't know if they still do this. Lord knows what sort of business model they use nowadays.)