Is there a Linux distro that's UNIX certified? Is there a Linux distribution certified with the Single UNIX Specification? What are the primary reasons that most distributions don't get certified?

Yes, there are

* Inspur's K-UX
* Huawei's EulerOS



They've been certified by the Open Group to be conformed to the UNIX 03 Product Standard. Currently no other Linux distros have the certification due to the high cost. The list of Unix-certified systems can be found below

* The Open Group official register of UNIX Certified Products
* <
* <



See also UNIX®-Certified Linux-Based Operating Systems