DISCLAIMER: Written below is an attempted explanation on the cost difference due to tariffs, and while I know about certain products for most countries for the company I work for, I'm not sure what deals, if any, Bethesda and or Valve has in place or how it applies to their products or the products they distribute respectively, with other countries. There are literally millions and millions of products out there and thousands upon thousands of different tariff codes (explained later) to classify them all.
You might not have the taxes that Australia has, but there might be tariffs involved for importing a product in your country, even it if it just a digital one (you're still getting *something*, that's the key). I deal with international trade on occasion, customs and duties are always a part of exporting/importing, and especially tariffs. Even if it is a digital download, it is still subject to tariffs. Though for Saudi Arabia (which is where I'm assuming you're from), the tariff is only 5% for HSTC 9504.50.00 but for there are also statutory rates that can climb upwards to 35%. HSTC stands for Harmonized Standard Tariff Code: this is a widely accepted and used set of codes which products are classified into so that the tariffs can be enforced on them more easily and quickly. For example, the description for a product under 9504.50.00 is " Video game consoles and machines, other than those of subheading 9504.30, and parts and accessories thereof.." I know it says "console", but I can't find anything for video games with another description. So when you figure in the exchange rate and the cost of that statutory tariff, you're looking at a total of 303.75 SAR.
Now you look at Canada, and there is no applicable tariff there thanks to NAFTA. The exchange rate though is about 1.32 today, which equates to 79.49 (plus applicable sales tax depending on province).
If Bethesda is using the statutory rates, 300 SAR is about the right price for them to maintain their desired profit margin.
And passing on the cost of tariffs is not something new to Bethesda, or any company anywhere in the world. The reason the cost gets passed on to the consumer is because if they didn't do that, they would eventually lose money on the sales in some countries. So instead of saying "we'll cover the cost for countries A, B, and C but not X, Y, Z", they just apply them to all.