Imagine how angry you’d be if you filled up at a pump advertising gasoline for $3 a gallon, then found out you’d been charged $3.35.

That sort of bait-and-switch pricing was standard practice in the airline industry until it was outlawed in 2012. Now, when airlines feature a price on an ad or website, the total fare has to be displayed prominently. They no longer can advertise a base fare in large type and bury the mandatory taxes and fees in the fine print.

So, consumers now have the information they need to make travel purchases quickly and confidently. They may be confused by extra fees for baggage or seat reservations, but at least they know the cost of more...