Originally Posted by
knope2001
Not sure if this explains what you're seeing, but in general Frontier might be punished for being more upfront with fees and taxes by appearing more expensive when they are not.
I know the DOT has issued a rule change on this that will make all airlines show the total cost at the start. Basically to address the type of situation you are discussing but the Airlines have filled for a delay in getting implemented from October to next spring sometime.