Linux's text-mode console comes from the bad old days of dumb CRTs prone to burn-in, and has built-in automatic screen blanking by default. It was of dubious utility in 1995, since CRTs are power-hungry fire hazards that are best not left unattended. The twenty-first century is now in full swing, and CRTs are so obsolete that you have to actually pay people to take them away.[0]
In 2011, a Linux box displaying an unattended text console is probably a headless server. One that will not see a monitor or keyboard unless, say, there has been a kernel panic. To aid the poor sysadmin who has been dragged out of bed at 3am to look at this, the cause of the kernel panic appears on the screen in a high-contrast black on black display to aid faultfinding. [0] Although the more common way to dispose of obsolete technology in Shepherd's Bush appears to be to dump them on the end of my street. Given one has to otherwise drag the stuff to Wandsworth recycling centre - a bus, two trains, two more busses, then a half-mile walk - it's easy to see why stuff gets flytipped instead.
