ummm....not true. Forensic labs have long used water traps to recover undamaged bullets fired from suspects weapons for comparison to bullets recovered from victims and the crime scene. Currently there mediums that perform equally well in less space and without the higher maintenance cost of water traps.
That’s the so-called “FBI tank”, made of stainless in New York state. It’s about 8-feet long, and about 5-feet deep. Shots fired into it have a diagonal “travel” of about 6-feet through water. (Less than 8-feet, due to the fill height).
I’ve recovered test fired bullets from a similar tank. The only bullet which was able to dent its nose regularly was the 40 S&W.