The operating system itself
Windows and macOS each maintain a catalogue of printer drivers and deliver them through their own update mechanisms. When a printer is connected or discovered on the network, the operating system frequently fetches a matching driver automatically, with no visit to any website. Driverless standards — AirPrint and Mopria — go further and let modern devices print to compatible hardware with no model-specific software at all.
This channel is invisible, which is why people underestimate how often it has already done the job.