Why do software developers make-pop up windows to update the software

I have so many pieces of software, and when I open them, the first thing that pops up is a menu to update the software. Before I can use the software, I have to close the menu each time or update it.

This is frustrating when you use a handful of applications, and each one does this every so often, each time an update is available. The software is working, and I can manually check for updates later. When I'm trying to get something done and use the software, the last thing I'm thinking about is taking a few minutes to update the software. I'm not concerned about what improvements might have been made; as long as it's working, I just need to get xyz done.

The worst offenders have this menu pop up a few seconds after opening the software, so you've already started using it, and then you get interrupted by the pop-up window. And if you click update now Yes/No and select No, it shows the update window again the next time you open the software. There is no option to Never show again.