You'll notice 1 extra candle in a dark room but not 1 extra candle in a lit stadium
In the 1830s, Ernst Weber found that the smallest change in a stimulus people can detect isn't a fixed amount — it's a fixed proportion of the stimulus already there. Add one candle to a room lit by one candle and everyone notices; add one candle to a room lit by a hundred and nobody does. Nearly two centuries later, Weber's law still holds for brightness, weight, loudness and price perception alike.