Question: Since when do they execute people so quickly on death row once the corrupt cop is exposed for being the real killer?
Answer: Time passes quickly. It doesn't show every minute of every day. When he was executed, several months, maybe a couple of years, had gone by. They wanted to show him finally deducing that Clark Kent was Superman.





Answer: To add to the other answers, in the U.S. the average time on death row before execution is close to 20 years due to lengthy appeals, legal challenges, evolving state policies, and complex judicial processes. In modern times, it never happens as it does in movies and TV.
raywest ★