Technically there is a driver for communication (generally only if using USB) but if we're talking symantics here, if the machine only connects over a network, and the data is processed in a RIP then sent to the machine over ethernet, you wouldn't actually need to install anything resembling a "driver" on your local machine. In this sense a driver would be just be the method of communication with whatever generic USB chipset epson pulled off the shelf and threw into these machines. Usually you don't need to even install that if you don't intend to use it that way.
So then technically the RIP is NOT a driver, but instead something that creates generic halftone data with a channel for each color and each possible dot size, puts it in a lightly proprietary format, and sends it over the network to the printer, which now has very little processing left to do.