Excellent observation.
But the pinging, and tensed faces, as they stare to the sky, makes for great drama for the movie watching rubes, but makes anyone who knows anything cringe.
You have to remember, we are simmers.
We strive for a game, where you die on your first patrol. We strive for a game to get harder as time passes, not easier as you upgrade past your enemies.
We are realists, and feel slighted when things are not represented properly. (U571? America found the Enigma? lulz)
So barring the subsimmers bible, (Das Boot) there is very few good sub movies.
Alot of us try to compare all sub flicks to that, and it is kinda unfair.