Amid calls for the government to regulate the disclosure of ancillary fees, airlines point out that the system is still evolving. Eventually fares will be customized to individual passengers, based on factors such as travel habits and frequent flier status. Additionally, fees will likely fluctuate according to demand, much the same as airfares do now. Such variables will make it hard to come up with a one-size-fits-all disclosure requirement, according to experts. "It's time for the regulatory process to admit that this is now a complex purchase," says airline consultant Jay Sorensen.