AFAIK the tests account for that and test different scenarios (i.e. not all unsafe modes are created equal; a product can still fail the relevant test cases in fast-but-unsafe mode). We pass the fast-but-unsafe tests (i.e. we fulfill the guarantees you'd expect in that mode), and also pass the stricter guarantees in the slow-but-safe mode.

However you're right that we don't pass stricter guarantees in fast-but-unsafe mode (but I'm not aware of any products in the space that do).