Singapore can do this because they're a city state without jury trials, a bill of rights, or the Kennedy v. Louisiana (https://en.wikipedia.org/wiki/Kennedy_v._Louisiana) decision. It's doubtful that the Supreme Court would allow a similar policy. If they did then the cost of appeals make this approach too expensive to implement it.

Yeah, executing drug dealers/smugglers at scale would require significant and likely negative rollbacks to our system of jurisprudence. The US used to do things like this though!

(I say likely negative because a system of trials that didn't cost 100k+ and take years for an actual defense would be a dramatic improvement)