I believe not all SPFI cars here in the US came with an O2 sensor. California has more strict emissions regulations than the rest of the nation. The California cars got O2 sensors, the cars sold in all other states do not have O2 sensors. I believe. Regardless, not all SPFI cars have O2 sensors from factory.
I have found it interesting that despite my car originally being sold in California, it doesn't have California-spec emissions equipment. It has the national standard emissions equipment.
I believe the national standard is just an EGR setup and a charcoal canister. No O2 sensor and no EGR temp sensor.