I’m a retired Naval officer (of the Royal Australian Navy) and while my career path didn’t involve as much time handling this type of thing as others did, I know more than the basics.
What you need to understand is that under certain circumstances it is normal for ships to be operating in close proximity to each other, and as long as everybody follows the rules of the road in those circumstances collisions should not happen.
But if somebody breaks the rules, it is possible for a situation to develop that another ship cannot avoid a collision.
Any large vessel should have competent people handling things and you rely on that being true on the ships around you.
Collisions like this are so rare, largely because most of the time it is true.
And sometimes you can do everything right (or think you have) and still something goes wrong - hence the double post!
But still, there is radar and AIS.