Does only "supply/demand" rule justify different prices for a digital good? Provided the network infrastructure costs the same for the seller (if things going on with net neutrality weren't to effect that), certainly considering the fact that an average citizen of a given "low average $ income" country would have less money available for digital products than say someone from Germany or U.S.A.

What are the mechanisms that justify large price differences between different countries (3x ratios or more) ?

Edit: Thanks for your answers.
As real life examples, what struck me is any app here https://steamdb.info/apps/ but as you suggested it applies for various digital goods on amazon and other sellers.
One explanation would be price discrimination.

Some people are willing to pay more for software than others. (Typically, we would expect such people to live in richer countries.) As a result, it will be in the interest of software seller with monopoly power to charge different people different prices.

In case this isn't clear, here is an illustrative example. Suppose that Microsoft is deciding how much to charge users for a digital copy of Microsoft Office. Legally, it is the only entity that is permitted to sell Office, so it has some monopoly power. Since we are considering digital copies of Office, its marginal cost will be essentially zero. Suppose that:


In Country A, all inhabitants would pay at most £10 for one copy of Office.
In Country B, all inhabitants would pay at most £200 for one copy of Office.


(Assume that no inhabitant wants more than one copy.)

What prices should Microsoft charge (to maximise profits)? Obviously, it should charge £10 in Country A (or £9.99 if you prefer) and £200 in Country B. Thus, even though the cost of production are the same in both countries, prices will vary greatly between them.

Note that this explanation only works if Microsoft can prevent resale - which it can, since it has a patent for Microsoft Office. Otherwise, someone might start buying copies of Office in Country A and re-selling them in Country B, a strategy which will render Microsoft bankrupt unless it changes its pricing.

Of course, it also assumes that price discrimination is legal.