A U.S. Senate subcommittee has held a hearing to question the growing use of airline fees to charge passengers for things like early boarding and better seats. Members of the Senate Permanent on Investigations say airlines have raised billions of dollars by imposing fees that are getting hard to understand and even harder to avoid paying. The senators and the Biden administration call them “junk fees,” and they say the extra charges are making travel less affordable. Some senators expressed frustration during Wednesday’s hearing on Wednesday hearing when airline executives couldn’t explain how they set various fees. Airlines say fees let consumers pay for things they want, like more legroom, and avoid paying for things they don’t want.