A minilab (in the context of photography) is a photographic laboratory for color negative processing and printing compacted into one small unit.
Minilabs can operate in daylight, and are usually quite idiot proof. The paper cames in light-tight rolls. The exposed film is fed into a slot, disappears into the guts of the machine, and appears as processed and washed strips.
As long as the chemistry is well kept, the apparatus is reasonably dust free and the operator has an idea of what he is doing, the minilab delivers fairly good prints: and, what is most important, cheap and fast.
The bad fame of minilabs is due, almost invariably, to poor operator training or attempts to skimp on maintenance.