It's old news know that The Beatles tracks are available on iTunes. Read more from The Wall Street Journal on how the deal was done. There are still a handful of artists that have i) the creative control with their record labels, or ii) control their own masters and can determine when and how their albums will be available for download on iTunes. There are varied reasons for not getting on board with iTunes, but one of the major concerns of acts like Kid Rock and Garth Brooks is the inability of the artist/label to control album only downloads versus singles downloads.
Your search for AC/DC, Kid Rock, Def Leppard, Garth Brooks and Bob Seger will only lead to "sound a-likes" on iTunes. On Episode 9 of the Entertainment Law Update Podcast, Texas music attorney Tamera Bennett and LA film attorney Gordon Firemark discussed with Jason Pascal, VP & Senior Counsel with The Orchard, the success to be had by cover bands issuing digital only releases when the original artists' tracks are not available.