Why do they not better check bodies of water?

"Officials confirmed a body found in an SUV that was submerged in a Pennsylvania creek is James Amabile, who had been missing since 2003. The SUV and body were discovered earlier in March by a group of YouTube volunteer divers who have helped crack cold cases around the country.
When the vehicle was first discovered, Ridley Township police noted that the license plate number matched that of Amabile's missing SUV, but a proper identification of the remains had not yet been made.
The vehicle was recovered from the creek Monday and the remains were identified Tuesday. The Delaware County Medical Examiner's Office was able to make the identification using dental records."

https://www.cbsnews.com/news/j....ames-amabile-missing