In short, they don't.
We are required to apply a 20% tax to orders placed in the UK and EU, but orders outside the EU are not taxable. Our website should identify the country you are visiting from, and adjust the prices accordingly. However, sometimes your connection will bounce across servers in other locations, which can confuse the website and change the pricing. To fix this, try clearing your cache, refreshing the website or connecting from a different device.
