Hello and welcome here.
PLease, when you want technical help always tell as the minimum amount of information to your potential helpers which version of openSUSE you use. We can not guess that. As we can not guess what you exactly did to configure that printer.
When you onlly want to know “Why is adding a printer so difficult with Opensuse?”, then you are in the wrong forum. We have a General Chit-chat where you can start a discussion about the relative easyness/difficultness of configuring printers. And why you think it is difficult and were it could be made easier.
But wen you want help with configuring your printer, you should provide more details (as said above). Which make and type of printer. What you did to confifure (using YaST? What do you see? where did you click? etc.).
And BTW URIs are Universal Resource Identifier. It may point also to things inside your system. It is not restricted to a network location.