There's no reason I should fear these now, but I was hit by a car back when I was in college (nearly 20 years ago now), and I had no health insurance and couldn't pay any bills. I was already barely affording to eat.
So, almost every single call I got was related to a bill that I knew I couldn't pay. The trauma of that has stayed with me to this day and I will often leave voicemails which are perfectly innocuous unlistened to for days, weeks, eternity....