They can be in more countries than just the Netherlands IIRC. And simple test-kits are available too - these aren't as good obviously, but can e.g. prove the absence or presence of certain (by)products.

Also, these tests are set up in a way that they are anonymous in a way that e.g. even if prosecutors could subpoena a test-location or lab to hand over administration, this administration won't contain any PII or even pseudonymous information.