I'm somewhere in-between your experience and the parent's. I've had 2-3 instances where it appears that someone put my email address on their account by accident, and I got their auto insurance claims, etc. There was no "click here to verify this is your address" email sent for those.

I also got a lot of email for a high school reunion where the school was named after someone who shares my name... And people routinely left off the numbers in the email address, ending up with mine.

The rest of the not-mine emails all look like phishing attempts to me, and not just mistakes made by some office worker.