The customs tax is in regards to countries/jurisdictions other than the ones with the Tesla factories. For instance a country like Israel might have a 20% tariff from Europe but 0% from China due to different bilateral deals so Tesla will send cars from there.
Israel is different than Dubai because literally a third of the population are in the tech space. Israel’s main export is tech and the tech ecosystem will build on-top of Tesla (Waze for example was founded here and there are many auto security startups for instance).