Music has become a ubiquitious presence in the lives of many people, especially those in modern, consumer-oriented societies.  We listen to music without even realizing it when shopping, strolling, driving, getting ready for work in the morning, and when conducting every kind of mundane task.  Restaurants pipe in music to help establish the desired atmosphere, stores broadcast music designed to subtly influence the mental condition of customers, and advertisers employ musical "jingles" to both introduct the products being marketed to potential consumers and to embed the product in the potential consumer's subconscious.  And this is all in addition to the conscious decisions people make during the course of a day to listen to the music they most prefer.  Additionally, the ever-present MP3 player or IPod complete with earbuds has become as common a sight as birds and traffic.  In short, the average person is subjected to music on a nearly-continuous basis throughout the course of a day.  With that kind of nonstop exposure, it is to be expected that many people would, over time, become increasingly inured to the constant sounds emanating from sterio and car speakers.  

People have come to take music for granted because there is so much of it and, in the age of instant downloads, it so easily available.  MP3 players, in particular, can be credited with facilitating this process by which music is increasingly taken for granted.  Whereas for thousands of years one could be expected to go through certain parts of the average day without access to music, today it is as much a part of one's attire as underwear.  When combined with the subliminal uses to which is routinely put by retailers and marketers, it is no wonder people have grown to take music for granted.