Because, unlike the 1980's and the USS Roberts incident, no mines were actually planted. Duh. This is a PR FUD disinfo campaign to sell Ayatollabooth tickets to split proceeds with Drumpf. When lacking a capability* and the media environment is weak and gullible, the next best and cheaper thing to doing the actual thing when it is difficult/risky to verify is bluffing.
* While Iran's separate, official Navy was essentially destroyed mostly in port and uncrewed almost like a decoy army, the IRGC's smaller vessels could plant mines if they so chose but being caught doing so would be a PR loss and would create hazards for friendly vessels of all kinds. It's better to go to great lengths to bluff low information, neurotic people that mines "exist" to get them to submit to tolls and inspections; perhaps release several videos of various IRGC boats "laying mines" (to be demined shortly afterwards) in unverified locations to suggest that it happened.
* While Iran's separate, official Navy was essentially destroyed mostly in port and uncrewed almost like a decoy army, the IRGC's smaller vessels could plant mines if they so chose but being caught doing so would be a PR loss and would create hazards for friendly vessels of all kinds. It's better to go to great lengths to bluff low information, neurotic people that mines "exist" to get them to submit to tolls and inspections; perhaps release several videos of various IRGC boats "laying mines" (to be demined shortly afterwards) in unverified locations to suggest that it happened.