When printers first started being used with consumer PCs, it was often an incredibly frustrating to get the device connected properly. Drivers were often broken, the user interface was unintuitive and just resulted in a hassle anytime you needed to print something from your computer. This has been alleviated in recent years with wireless printers and even the work that Google has done with its Google Cloud Print service. Still, it could always be easier and this is why Android Oreo's default printer service is using technology that was contributed to AOSP by Mopria.
For those unaware, a print service is an application that sits in the background and attempts to discover printers that are connected to the network you're on. It will then present these printers to the device's print framework so the platform can try to use it. With earlier versions of Android, users would often times need to search for a 3rd-party print service on the Google Play Store in order to print something from their smartphone or tablet (unless it was compatible with the Google Cloud Print service).
With the Android Oreo update though, we now have a default print service that enables people to print on modern printers which support the Internet Printing Protocol (IPP) without needing to use any additional applications. If you have an older printer that does not support the IPP, though, then you will still need to install the app recommended by the PrintRecommendationService. You can learn more about this from a Google I/O 2016 presentation here.
This change is all thanks to Mopria and the Mopria Alliance which was founded by Canon, HP, Samsung, and Xerox. Over time, this alliance has grown to 20 members worldwide with new additions including Adobe, Konica Minolta, Qualcomm, Lexmark, Kyocera, Toshiba, Brother, Epson, Fuji Xerox, NEC, Pantum, Ricoh, YSoft, Sharp, Dell and Primax. Statistics show that Mopria certified printers make up 97% of printers sold worldwide so seeing this technology used in the default printer service of Android 8.0 Oreo is a big deal.