Korean Air charges $100 per extra bag, airlines mishandle 33 million bags a year, and a family of four often brings 3+ pieces of gear on a Seoul trip. Here's the math most travelers skip: why renting a stroller, car seat, Dyson Airwrap, and 4 other essentials in Hongdae usually costs less than flying them in — backed by 2025 SITA data and real Korean Air fees.