*you* don't use the driver, there's no actual file that IS the printer. It disappears into hardware abstraction code and gets dealt with like that. I don't know all that much about how it works, but the basic point here is there is no c:\windows\systems32\davesprinter.prn or something similar.
Actually, there are shitty remnants of this is the DOS environment I believe. On unix you can run "echo TEST > /dev/ttyS0" which would write the word "TEST" to the first serial port, there IS a file at /dev/ttyS0. On windows the same would be "type TEST > COM1" But note here that COM1 is NOT a file. It was just a nasty nasty hack where using the word "COM1" would be arbitrarily pulled out of the ether and sent into the 1st serial port, rather than a file called "COM1"