Is it a red flag if they are so much cheaper than Most every other airlines especially Southwest? Like a Southwest costing $230 while frontier only charges $89 for the highest business package ticket that includes bag fees? For the same city pairs and time?

Edit: Is it Similar to spirit, Volaris, or the European equivalent of Ryan air or easy jet?

In 2007 I remember they did charge for snacks but not water and carry ons were free but I guess they drastically changed business models overtime?

FYI they took over full service Midwest airlines back in 2008. The polar opposite of low cost airline.

Normally plane tickets are very pricy last minute even for cheap airlines. I am guessing staying cheap until the gate close is a big red flag that people just arnt buying it.