Is it common practice for countries to charge a fee to international travelers?

Yes.  In fact, the $14 fee for eligible travelers who come to the United States under the Visa Waiver Program (VWP) is significantly lower than what travelers pay to visit other countries.  To put this in perspective, it's important to note that on average other countries charge entry and/or exit fees of nearly $60 per traveler per visit—usually attached to taxes and fees on travel purchases such as airline tickets.  Some of these fees are as high as $150 per traveler.  In contrast, the $14 Electronic System for Travel Authorization (ESTA) fee covers travelers from VWP markets for a period of up to two years regardless of the number of visits these travelers make to the United States.