Not every California SMOG inspection works exactly the same way. The vehicle year, the DMV notice, and the station type all affect what kind of test you need.
Used for vehicles that DMV specifically directs to a STAR-certified station. Not every local shop can handle these directed inspections.
Some stations only perform inspections and do not handle emissions repairs. Drivers may be referred to these depending on the vehicle and program rules.
These locations can inspect the vehicle and, when appropriate, repair emissions-related issues if the vehicle does not pass.
Many 2000 and newer vehicles are inspected through an OBD-based system. That is one reason readiness monitors and check engine light issues matter so much for newer vehicles.
Some older vehicles use testing procedures that can include emissions measurement equipment different from what newer vehicles go through. That is why the testing experience can vary depending on the vehicle year.