Prices should differ across different countries, but companies must not only reap the benefits but also manage the costs and avoid the pitfalls.
Prices are almost never the same in international markets. They vary due to taxes, cost structures, local market needs, currency exchange rates, tariffs, differences in competitive situations and a myriad of other reasons. They even vary because this is the way it has always been. If looking at different industries, consumer products (CPG/FMCG) have more than 100% difference in prices, with even regional differences in e.g. the European Union of up to 50% for the same product. Car manufacturers are well-known for their price differences and even relatively global products such as computer software has had a number of bad PR cases where e.g. Australians would pay twice as much for Adobe software as US customers.
But international price differences are more good than bad. Here is why.
Not everybody is willing to pay the same. Some people are willing to pay more than $1000 for a phone; others only want to pay $200. The same really applies across nearly every product or service category. So what companies routinely do in their local markets is to segment the market and do product differentiation (e.g. iPhone X, iPhone XR, iPhone XS) to meet different levels of customer needs and levels of customer willingness-to-pay. Sometimes the product or service differentiation is even minimal (e.g. booking options) and the product nearly identical but still the price varies considerably, think e.g. flights, last-minute hotel rooms, concert tickets, etc. In other words: people are willing to pay different prices in a single market, and the sound pricing strategy to address this is to have multiple price points for the same or slightly varied product/service.
If the vendor only has one price, e.g. represented by the green area, then the total addressable market is limited and the potential business also limited. But if it is possible to product differentiate, or simply price differentiate (within legal constraints of course), then the addressable market is bigger and more customers can be reached.
In terms of real-life optimization of prices, it can look something like this for 3 different segments: