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That’s only really done now for nonrevenue (employee) travel and changes in existing itineraries (trying to get an earlier flight, getting rebooked to a full flight because you missed your connection and that’s the next one, etc)
Some flights during certain seasons (spring break in Florida, for example) are so full that you hardly stand a chance of getting on, and of course that’s the airlines’ fault
No, if you find a flight you like and, instead of putting your credit card information right there, you drive to the airport, pay for parking, wait in line at the ticket counter, tell the agent you want to buy that itinerary you just found online, argue with them when they say they can’t/won’t so it because it’s freaking Frontier, pay for your ticket, walk 10 minutes back to your car in the parking ramp, pay for your hour of parking, and drive home.
Probably not worth it for a single person/purchase, but if it’s charged per person, per direction (I think it is but not sure) and you’re paying for your whole family it may be worth it.