Indeed Landesk Data Analytics (LDDA) does it through the Discovery Services. LDDA just does an SNMP scan and puts what data it returns from that scan into inventory. As far as documentation goes (see Data Analytics Self-Paced Training) we will pull whatever data that the hardware supports based on the SNMP protocol. This includes things such as printer ink level etc. The Discovery Services tool it just a way for customers to run these SNMP scans (which were widely available previously) and store it in LDMS for reporting.
You’ll note that the community article has some details on Printer specific information. However SNMP scans is much more than just printers. SNMP is a standard connection protocol (just like HTTP and even ODBC)..
I hope it will clarify things up,