The 12 new allegiant planes were a one-off deal from airbus, because they were the end of the line and came with extremely attractive financing and pricing. In the last earnings call, it was mentioned that the purchase and lease-back deal actually contributed to earnings due the amazing deal.
Not to disparage WN, which has always been amazingly managed. But in your previously deleted statement, saying they pay for the planes is similar to someone saying they bought a house with 20% down.. and they own their house. They still need to make the payments, and there is still a financial duty to provide a good return on capital.