Honestly because many passengers value carry-on bags more and are willing to pay it for the convenience. Also, it cuts down on delays to incentivize people to check bags. Having worked for an airline that charges for carry-on bags, I cannot recall ever taking a delay for running out of overhead bin space.

The high cost of carry-on bags in 2026 is driven by the airline industry's shift toward unbundled "Basic Economy" pricing and the operational need to reduce boarding times. By charging for overhead bin space, airlines like Spirit, Frontier, and increasingly the "Big Three" on certain routes, incentivize passengers to travel with only a small personal item that fits under the seat. This reduces the "bottleneck" in the cabin aisle during boarding and minimizes flight delays caused by gate-checking over-sized bags. Additionally, airlines have invested heavily in larger overhead bins (like the Airbus "Airspace" L-bins), and they use carry-on fees as a high-margin revenue stream to offset rising fuel and labor costs. In some regions, such as India, strict "One-Bag" rules have been implemented not just for profit, but as a mandatory security measure to reduce terminal congestion and speed up throughput at X-ray checkpoints.