Hi Andy, in principle you always have to pay Swiss VAT over the total price. As shipping is on us and we don't calculate the 6% Dutch VAT with order to Switzerland, you pay the normal Jake price -/-6% Dutch VAT +/+8% Swiss VAT.
I can honestly not give you an answer to why you sometimes don't have to pay customs/VAT, so it would indeed be interesting to see what happens to with the other Swiss' orders.