Airports in the US are usually not secure, but the passenger terminals usually are. It makes sense to secure the passenger terminals instead of the individual

Airports in the US are usually not secure, but the passenger terminals usually are. It makes sense to secure the passenger terminals instead of the individual planes to reduce the amount of equipment and staff needed. LAX for example has 150 gates across 8 terminals. Securing each plane would mean placing TSA agents, metal detectors, scanners, and X-Rays at 150 gates instead of just 8 terminals. Come to think of it, US airport security is pretty weak compared to an airport like Manila NAIA (in the international terminal). Passengers get checked curbside for passports and tickets, and again at the door. Then they must pass through metal detectors and bag scanners to get into the ticketing area to get boarding passes. Boarding passes and ID are checked again at immigration. Then there is another bag scan and metal detector to get into the passenger terminal. The last check is the most thorough. To get to the individual gate, there is a checkpoint with one station where all carry-ons are opened and inspected, one station where passengers remove their shoes for inspection, and a final station for a pat-down by security. This last security check must be repeated every time you go to the bathroom or visit the shops or restaurants.