No, it isn't. It's uniformly terrible when you choose the cheapest option which coincidentally is the driving force behind air travel reducing extra comforts.
In that regard, Spirit was refreshingly honest because they didn't even pretend to care.
That depends on how you define "Europe".
Europe-the-continent, Athens to Reykjavik is roughly the same distance as NY to SF.
If you define Europe as "Any territory belonging to a European country", then the longest domestic flight is between Paris and Saint-Denis, Réunion. It's about 9000 Km, which is twice the distance between NY and SF.
Tenerife is quite a popular destination, and is also relatively far from the mainland.
Spirit is no different. They hate you and they make sure you know it.
I can't vouch for frontier I've never flown with them ..not yet at least.
If you try to get the things without paying, eg bringing too much baggage, that's when they fleece you. But just follow the rules and it's fine.
How were your reclining seats? And how long were your flights?