But then, when you landed, you became a sovereign consumer again. You had your choice of car rental companies, hotels, and restaurants. You could shop around for the best prices, carefully measuring price against quality, and exercise real buying power. The answer is that airlines are not a naturally competitive industry. They require very expensive capital equipment that needs to fly mostly full to be cost effective.
Big airlines have the market power to crush little ones.
And airlines depend on public facilities, namely airports. All of which is why they used to be regulated. More than 20 years ago, however, the fathers of airline deregulation thought that airlines could be just like car rental companies or restaurants. Stop regulating fares and routes, get the government out of the way, and new, cut-rate carriers would offer better service or lower fares. But it hasn't worked out that way.