Calling it an "accident" is doublespeak so you can wave your hands and go "I had an accident, oops, it couldn't be helped."

Making it seem like it was just your fate that day. Which if it was at-fault, it certainly wasn't. It sounds a lot better than "I am either negligent or incompetent and shouldn't be trusted with piloting a 2-ton hulk of metal."

If you checked your blind spot every time like you ought to, the blind spot detection is at best a minor additional safety backup. I see a lot of people relying on it instead of actually doing that, and the systems aren't perfect. (One good example: Someone else is starting to merge into your blind spot but hasn't gotten in the lane yet).