Why is Deployment so Hard?

There are so many tools available to help make deploying code easier but it’s still one of the most feared/hated parts of software development for most people I know.

What is it about deployment that makes it so hard to solve?

Is it the number of steps you need to go through (testing, building, setting up environments, etc)?

Is it fear of production bugs that leads to less frequent releases which then increases bugs?

Or is it having to work with a maze of different deployment options for each major cloud platform and just the challenge of running your code on a computer you don’t have in front of you?

Or is it trying to optimize for cost vs ease of use and complexity?

I have used kubernetes and terraform which is a lot of overhead and leads to high expenses for a small app. I’ve also used Azure Web App Service which is super easy for a lightweight web server and front end.

I’m curious what have other people tried and what has been your best and worst experience with deployment?