We do have a shipping policy that's been on our site stating that customers are responsible for any Customs tax that may be incurred during shipping. Since Customs tax vary from country to country, its difficult to charge it upfront unless we have a distributor in that country.
Here is the link to our shipping policy: https://www.keepkey.com/legal/shipping-policy/
We're working on getting more and more distributors around the world so we can avoid this type of issue in the future.
Here are our current distributors: KeepKey Resellers