Writing Checks
Baby Boomers tended to use checks when paying for what they bought, unaware that they were carrying up the queue. It would be more efficient and convenient to bring a small card instead of a stack of checks. We were also annoyed by the customized checks that had puppies or kittens all around them. It would look terrible, especially when we were paying for colonoscopy.
Landlines
Landlines were stuff we could stick to the wall, and while they might be free, we could not see the point of owning one in our house. As an alternative, we could buy a mobile phone and use it anytime we needed to. We could guarantee that we could live just fine without the landlines.