It's a "history" thing...
Back in the '80s, music/movies/cartridges all required that the delivery media (tape/CD/cartridge) all be physically present to enjoy the "product". It was quickly realized that installable media (software) did not suffer from that limitation, in that once the software was installed from the delivery media said software could be executed without the original media present.
CD copying in the 1970s, no EULA. MP3 copying now still no EULA. Bootable floppy based games still had EULAs even though the game could only be played with the floppy in the drive. Current games that require the CD to play have EULAs. Versions of Windows that only install on the type of OEM hardware they were made for (DELL Windows for example) still have EULAs.
So, the EULA was devised to protect the manufacturer. I remember a day when all an EULA really did was prevent (occasionally restrict) multiple installs and mandated the destruction / transfer of the original media, backups, and manuals/paperwork made when you were done with the software...
Heck, I remember a MS Office EULA that allowed it to be installed on all of an owner's machines (office comp, home comp and laptop), as long as only one machine was using it at a time (ie, if I was at work typing documents wifey couldn't be at home storing recipies...)
Also, remember that "back then", pirates had to copy to a blank media in order to create their pirate copies, it was only in the past couple of years that being able to rip/pirate movies over the net became common...
I remember game software designed for "Hot Seat" play but the EULA forbade it.
The basic thing here is what makes software different so it can get away with EULAs when books (tried and failed a century ago) don't, music doesn't.
Myself I question the fundamental legality of the EULA and its enforceability.
On the other hand, if you're getting screwed out of millions of dollars restricting technology in an attempt to prevent piracy starts looking a lot more attractive.
I have yet to see the evidence of that. How many of those pirated versions are like the "pirated" copy of Sim Earth I had? I had a legitimate version but the installer wouldn't work (turned out I had too much free memory) but the pirated copy did. The only people who are stopped by DRM are those who are legitimate customers who refuse to pirate it. The pirates just download the cracked copy.
Have you ever seen how the BSA calculates the "cost of piracy"? They estimate the number of computers in use, do a survey of the software in use and extrapolate from that the number of "pirated" copies at full retail price. Sounds fairly decent until you consider the machine I'm on runs a free copy of LinuxMint but is assessed by that system as a "pirated" OS. All my machines have OpenOffice (so does my mothers) more machines assesed as using "pirated office software".
Do you remember Lotus 123? Wonder why they dropped their DRM? It cost them more than creating and maintaining 123 itself.
So what it amounts to is:
1/ DRM only stops those who were not pirates anyhow.
2/ It only harms those who are not pirates
3/ It costs money which makes the product more expensive and therefore more likely to be pirated as too expensive to buy.