I had a very interesting experience with footpatrol related to this. They also do not deduct tax and when I got in touch with them because they messed up my order (very typical for them, look for reviews about them on trustpilot), I also asked why they don't take out tax since I am ordering outside of EU.
You won't believe what a girl from their customer service replied to this... first she offered a 5£ discount for the inconvenience...really? Then she told me that based on UK legislation (!) they are obliged to impose tax on any order no matter where the purchase order comes from. She then added that anyway, because of the recent BREXIT, they are no longer part of the EU, so they don't follow any EU guidance that may refer to excluding tax.
I just replied saying that she represents a business in the U.K. and even though she probably needs pocket money to support her studies and being part time of footpatrol's cs could be a solution towards that, she should be very careful on her email wording as people would be really interested to know what is footpatrol's opinion on the BREXIT (just a referendum result so far with no actual consequences/effect at the moment in terms of UK and EU status) as well as its effect on business practices. I never heard back from her.
And then I thought and no offence to any Brits here, that people like her decide and vote on such serious matters.