What happens when there is a spelling error in your domestic plane ticket?

I booked a ticket for one of my friends recently and made a spelling error (just one letter) We contacted the airplane carrier to change it but they made such a big deal out of it saying that it is against their policy and that we have to book our ticket again. I know that they ask for Government ID proof when cross checking the ticket at the airport but how big a problem is this?
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How to rectify Spelling-errors in Airlines Tickets| Spelling mistake
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