In the US, airlines don't set the transportation security guidelines and decide what can or cannot be bought in luggage or carry on. That is the job of the Transportation Security Administration (TSA).

TSA publishes that up to 3.4oz are allowed in carry on: https://www.tsa.gov/travel/security-screening/whatcanibring/items/peanut-butter

The reasoning behind what items and/or amounts are allowed/disallowed usually is not shared outside the agency except in obvious cases. I would guess that it is feasible to hide a sharp object or small explosive in a peanut butter.

Governments are in best position to know what attackers attempt and set policies and communicate out to their agents. If airlines were to hold responsibility for setting and enforcing policies like this, they would become targets to receive the customer displeasure when items are not allowed/confiscated and would set rules keeping customer displeasure in mind and erring on the side of pleasing customers.

By airlines not holding that responsibility, the airlines can correctly claim "Sorry, I understand the frustration but we don't make the rules" and direct displeasure to the TSA.

In the US, airlines don't set the transportation security guidelines and decide what can or cannot be brought in luggage or carry on. That is the job of the Transportation Security Administration (TSA).

TSA publishes that up to 3.4oz (100ml) are allowed in carry on: https://www.tsa.gov/travel/security-screening/whatcanibring/items/peanut-butter

The reasoning behind what items and/or amounts are allowed/disallowed usually is not shared outside the agency except in obvious cases. I would guess that it is feasible to hide a sharp object or small explosive in a jar of peanut butter.

Governments are in the best position to know what attackers attempt, and set policies and communicate out to their agents. If airlines were to hold responsibility for setting and enforcing policies like this, they would become targets to receive the customer displeasure when items are not allowed/confiscated and would set rules keeping customer displeasure in mind and erring on the side of pleasing customers.

By airlines not holding that responsibility, the airlines can correctly claim "Sorry, I understand the frustration but we don't make the rules" and direct displeasure to the TSA.