Sorry, but by "pretty much anywhere in the world" you clearly mean "first world". If you live outside of US/Canada and EU it is much harder to obtain books legally. Publishing agreements usually cover specific countries, and no-one cares about, for example, selling books in English in Central Asia. So even if you have means to pay for the book (which can be challenging - and I'm not talking about "having money" here, I'm talking about "technical possiblity" - Visa and Mastercard are not as universal as they might seem from the first world), most of the time no-one can or wish to sell it to you legally.
Interesting that Steam solved most of that problems for game distribution though. They have worldwide publishing agreements, regional prices AND good support of local payment providers in many countries. I think a lot of people underestimate how these factors allowed Steam to overtake piracy.