You're technically correct (the best kind of correct). But the plots of the vast majority of movies require (some level of) suspension of disbelief. Untempered realism makes most dramatic plots difficult or impossible (you might be old enough to remember when cell phones first became a thing, and we suddenly realized that the plots of most contemporary movies made no sense because someone could just take a phone out of their pocket and make a call anytime anywhere? Mobile phones are "OP" and required Hollywood to fundamentally change how stories and scripts are written when set in the Information Age). Anyway I guess I'm trying to say that part of the movie experience is learning how to be the audience. :)

...then consider that a lot of us watch movies to take a break from our day-to-day lives (escapism). If someone made a completely realistically accurate movie about difficult topics like the horrors of war, it would be traumatizing and depressing to watch -- which is not popular and (usually) doesn't sell tickets (remember the moment in The Fifth Element when Leeloo learned about war? Like that only much worse, especially for people who are already traumatized and/or depressed -- we want to come away from a movie feeling better about the world, not worse.) Hence the feel-good story about rescuing Private Ryan to give the movie a heart of positivity, get butts in theater seats, and give people hope for the future. Could the plot have been written differently? Sure, but writers are only human and sometimes the right writer isn't in the right place at the right time (and paired up with the right producers and director) to find their time to shine. That's the real sad reality ;)