You missed a point: always assume that people will do something that you never dreamed that they would do. You may not even imagine what it is and they will do it after you have put the app into production. It’s just worse than those that you have listed.
When I joined EDS in 1985, I added this step to my first estimate: “Post implementation adjustments — x hours”. They had no concept of estimates in hours. They used work-months. Then, they had never heard of post implementation adjustments and did not want it included (I made that term up and had been using it for years). Customer VP’s liked it, though. Nobody complained about bugs, cumbersome design or any other flaws because they were expected and knew that they would be fixed.