I don't see how, for instance, with a Austrian customer of a Belgian data center operator, the Belgian data center operator does not have a legal obligation to

I don't see how, for instance, with a Austrian customer of a Belgian data center operator, the Belgian data center operator does not have a legal obligation to form a secure database pipeline connection and replicate everything directly into the NSA. Obviously whatever signals intelligence gathering method or data copying the NSA might be doing in Western Europe could very well exist, but it's not a defined requirement for that theoretical Belgian ISP.