Why do countries just drive away when they encounter pirates?

Pirates are now mainly active in two places. One is a well-known Somali pirate, and the other is a Malacca pirate in Southeast Asia. Because running boats often pass through these places, it is the only way to Europe. Every time they pass through here, they also need anti-piracy drills and safe evacuation training. The lights on the ship should be limited and guarded by special personnel, so the speed of the ship is generally not full (fuel saving). But what is the reason why pirates always emerge one after another? First, many pirates are poor or fishermen, and some don't even know about warships. Before, there was a true joke that several Somali pirates were going to rob a ship at dark. When I got up, I opened the hatch and saw that they were all officers and men. After being arrested, they realized that this was a French warship drifting. It's true. If you don't run the boat or pass by here, these stories are rarely heard. These pirates will be tried after being arrested, and then put into prison, but too many pirates have been arrested and put into prison for a period of time and then released, because they didn't really commit any major crimes, but they just tried but failed. The released pirates will return to their old jobs and may become small leaders because they are experienced. Second, except for the hijacked merchant ship, other speedboats and small pirate ships are actually small fishing boats. When the warship approaches the search, they will hide their weapons at the bottom of the ship, take out fishing rods and nets and pretend to be fishermen, and continue to look for robbery targets after the warship leaves. Therefore, the pirate ship is not as flamboyant as in the movie Pirates of the Caribbean, and it is difficult for warships to determine whether it is a pirate ship. Third, now that the situation in the Middle East is so chaotic, every country is looking for opportunities to insert its own forces and has legitimate reasons to send warships to some sea areas. Somalia is a very poor country. If the United Nations is really determined to improve the conditions there, there is no problem for the United Nations troops to wipe out the local pirates. Countries such as Britain, the United States and France can successfully fight Iraq and Libya, and Somalia is not a problem. However, no country is willing to do so, because it will not benefit from its efforts to fight Somalia. Pirates have been killed, how can British and American warships run around the world blatantly?