User authentication on the device
Most operating systems allow you to set permission on who is able to perform what type of printing services on that printer. For example, you can specify that everyone can print to that printer but only certain people can manage the printer.
Hard drive caching
When you hit print on your device, your local system creates a file of the output. The output file is then sent to the print server which is often contained inside of the printer itself. The output file is put into the print spoiler to await printing. The print spooler is in charge of what print jobs print and at what time and in what order. Once the printer is available and your print job is at the top of the print queue, the spooler prints your job onto the printer. Once your job is complete the spooler file is deleted, but this may not always be the case. Sometimes the print file is kept on the system until space is needed. That means if someone gains access to these print files they could potentially have access to anything you’ve printed.