This is not a new practice for Amazon. This happened to my Significant Other during holiday shopping five years back. Utterly confused when we saw it on the bill. Bill searching, etc. My SO remembered seeing something, but thought it was just a one month trial, not signing up for a subscription. A bit of shame for feeling sucked in.

The only difference between our stories is that upon doing the research, we decided that Prime was a good fit for our Amazon purchasing patterns and haven't canceled yet.