if I hadn't double checked I'd have gone into the side of him
If that had happened, you’d have been at fault.
It’s nice to let people out, but if it came to an insurance claim, or worse still, a prosecution in the event of death or injury, you’d cop all the blame, unless they were over the speed limit or under the influence.
If it’s a route you do regularly, you know where there may be issues and drive accordingly, but if you’re unfamiliar with the route, you won’t be aware that it’s common for people to push their way out at that junction.
It’s nice when people let you out, but you shouldn’t expect it as a matter of course.
Now then, do you always wave to say thanks or do you do that weird indicator thing?