That's called PPBM (Positive Passenger-Bag Match). However, PPBM is not required on US domestic flights. I had a few occurrences where I checked my bags several

That's called PPBM (Positive Passenger-Bag Match). However, PPBM is not required on US domestic flights. I had a few occurrences where I checked my bags several hours before my flight and had those bags arriving before me (on an earlier flight) at my destination airport, waiting for me in the airline's luggage office. The TSA relies on screening every bag to prevent incidents, rather than assumptions-based reasoning. There is a PPBM requirement for international flights though, including those leaving from the US. While security is the reasoning behind it, I suspect that customs and immigration compliance also play a role.