Of course, the majority of mankind cannot use the Internet nowadays or in the near future, since they live in countries which lack the necessary economical and technological infrastructure. But the Internet causes polarization in developed countries, too: people are divided into Internet users and Internet illiterates, and as the use of the Internet grows and often replaces traditional methods of communication, the illiterates may find themselves in an awkward position.

Is it acceptable to use economical in the above passage?
No, because meaning 1 here:
which shows that the synonymity between the two terms isn't anymore valid (it's archaic)
And the other meanings don't correspond.
 Marius Hancu's reply was promoted to an answer.