If you don't feel like flying today, that's fine with them. No change fees. However, sometimes they don't feel like flying either, and you also need to extend them the same courtesy.
Airfare: $0.01
Taxes and fees: $18.97
Total: $18.98
In this case, I searched for a flight to Atlanta - Frontier was $49, Delta was $250. After going through the checkout process, I paid exactly $49 for my Frontier flight. I need to add a checked bag, which it looks like they charge $50 for, but $99 is still << $250.
When I lived out of state, I'd go up to visit family for the weekend with just a laptop and 2 changes of clothing. The dirt cheap budget flight options were amazing.
I appreciate Southwest's philosophy but it isn't immune from trying to squeeze more revenue out of each trip - they just do it differently.
But a fee for lugage is very natural. Handling lugage has a clear cost. It looks natural to unbound it.