Inkjet printers spray liquid through nozzles finer than a hair. If the printer sits unused, the ink at those nozzles dries and blocks them, which is why an occasional printer produces streaky pages while a busy office machine rarely does.
Laser printers use powder fused by heat, so they do not dry out. Their failures look different: faded patches when toner is unevenly distributed, or repeating marks down the page when the drum is worn.
Low-ink warnings are estimates, not measurements. Most printers count pages and coverage rather than sensing the fluid, so a cartridge can print dozens more pages after the warning, or run dry sooner if you print heavy graphics.
Third-party cartridges usually work, but printers may report unknown levels or refuse to show status. That is a licensing behaviour rather than a fault, and quality varies far more between refill brands than between original ones.