I wouldn't say so. Pirating textbooks is much harder than pirating music. The entry point is $0.99 for pirating music; it is $150+ plus scanning (or somehow obtaining a PDF version of the textbook) for textbooks.
Undergrad here; not true. I'm currently building a scanner because I hate carrying my textbooks around campus, and any one book is heavier than my laptop. I did search for pre-existing scans, but most of them don't exist. By the way, scanning is only $150+ if you count the cost of a camera. If you already have one for other reasons, or can borrow one, you can make legible copies for free, or spend a little to make a platen and fixed camera mount for better copies in less time.
I'm speaking anecdotally, of course. I've had pretty good luck finding scanned versions of my engineering textbooks, to put onto my iPad. There's only been a couple of obscure or OOP books that haven't been available. It does take some digging, of course. The initial sites were quite open about it, but the publishers have driven it underground onto private sites.
I would say the entry point is less than 100$(nikon coolpix) plus making photographs. Scanning takes so much time. Good ones uses 600$ canon or nikon(you can share use a friend digital camera)
Today people can share(or rent) relatively expensive scanners(1000$) with ultrafast feeders(any book in less than a minute) it they don't care about destroying the original book(just "guillotine them"). I had so many books that I did it with hundreds of them, my entire collection will be digital some day.
It hurt the first time I did it, but there are so many advantages(you can move with all your books, no weight, search funtion, indexing, digital notes)
A friend of mine in Japan had 50 books scanned to OCR'd pdf for him by a scanning service (scanning was desctructive). Took 2 weeks and cost 200yen/book.