Bakersfield has literally zero premium demand. Other than the oil business, which is more bust than boom here, there are no premium customers on any kind of a regular basis to or from BFL. Pre-Covid, FAT had more seats available in the first 30 minutes of any day than BFL had for the entire day.
Nearly every major airline has tried BFL at some point, and almost all have run away quickly. After deregulation in 1978, the airport was, literally, a ghost town. Small commuter airlines came and went, but nothing lasted. AA returned with DFW service via SBA, followed by UA and their quirky SFO and DEN routings. Continental tried twice - once in 1982 of IAH via LAS, but that lasted less than a couple of months, and then again in 1987 after taking over the old Frontier. They even put a billboard in town, saying, "you need to fly us, or we're out of here!". And they were. America West tried in the late 1980's, with four flights a day to LAS. Why not PHX? I have no idea - but almost as if it were designed to fail, they pulled out, only returning in the 2000's (finally to Phoenix!). SkyWest flew as a Western/Delta connection to LAX for a while, and one EM2 to SLC flew for a few months, but it was gone quickly. Delta tried again in the early 2000's, but the economic collapse meant yet another pull-out.
Zero premium demand + too close to LAX = nothing, really, forever and ever.
BFL airport itself used to have a billboard targeting driveaway-to-LAX pax on northbound I-5 near Magic Mountain saying something like "If you flew from Meadows Field you would already be home".
I remember that billboard! It always marked the one-more-hour-to-mom's-house-in-Bakersfield point, usually after a hellish drive through all of Orange and Los Angeles Counties. I never figured out the purpose of that - someone in the city HAD to have known that local premium demand drives new air service, not denizens of Bakersfield being shamed into flying a more expensive and lesser convenient route just to be loyal to a home airport! But from the same minds who have conspired to keep Bakersfield an endless suburb without much of a business climate comes the idea of ringing the bell of shame from "Game Of Thrones".
The Bakersfield area has supported scheduled LAX bus shuttle service for years (temporarily suspended due to COVID I hear). The Fresno area has never had a scheduled airport shuttle to the Bay Area or SoCal airports, just that further driving distance.
And it used to be a bigger deal - now, even before COVID, that was dying off. The last times I let my mother use the bus service, the times were limited, and their website wasn't working. In this day and age, a non-functioning website is an anchor on a sinking ship. It was - and still is - easier for mom to take the Amtrak bus & train to San Diego, stay with me overnight, fly out the next morning, and repeat the process in reverse than it is for her just to get to LAX.
BFL as you said has seen everyone try it. Allegiant pulled out after only 9 months and Mexicana lasted about one year. AeroMexico and Volaris have never seemed interested in replacing Mexicana, probably due to the LAX proximity.
I have nearly lost track of everyone who came in to BFL and pulled out. Air LA had a mini-hub here for a few weeks, but POOF! Just like flash paper, they were gone. The newest Frontier tried x3 weekly to DEN, but the times were awful. Allegiant and America West could neither one make LAS work from BFL, even with connections. Either Allegiant or Frontier was the last mainline service there.
The 2006-built terminal at BFL is a nice facility. Three jetways and a much better passenger experience than the old terminal. But I understand the airport budget has been strained by the debt since there is little traffic and revenue. I read some of the debt was written off.
The economic collapse of 2007 hit BFL hard. Continental to IAH, gone. Of course, a large part of that was the equipment "agreement" with ExpressJet, who operated that flight. A temporary suspension turned into permanent. Delta/SkyWest dropped BFL-SLC from twice to once, then gone. HP dropped LAS at this time, but kept PHX. Only UA seemed to do well, actually increasing DEN to x2 during this time. SFO, however, has always been iffy.
I LOVED flying through BFL during the ExpressJet branded flying from SAN...42 minutes with a beverage, or 4+ hours in Los Angeles traffic...hmmm...
I always thought BFL made a mistake in 2006/2007 by spending $4 million to expand and remodel the original terminal building into a separate international terminal/customs offices. That created two terminals nearly 1 mile apart with duplicate parking, concessions, maintenance, etc costs. Instead I thought they should have spent less to build just a FIS adjacent to the then-new Thomas terminal for arrivals/customs and use the Thomas terminal complex for international departures, parking, concession services, etc. to reduce duplicate services and costs, similar to the approach FAT used.
I think the reason for this set-up was both availability AND a lack of demand for service at the new "international" wing. Bordering on the absurdly outdated, the old terminal was, at least, a standing structure that was fairly quickly converted to international service based on interest from Mexicana. Given that there would be zero connecting passengers, a shuttle between the terminals was unnecessary for one scheduled flight to GDL. And given also that BFL-GDL was entirely VFR customers, a red-eye with no frills was exactly the clientele Mexicana was looking to capture. And if you remember the old terminal, food wasn't a priority. In fact, it didn't exist. And with a red-eye flight like this, it would have been too expensive for a building that is only busy for maybe 1-2 hours a day.
My deepest hope growing up in Bakersfield was that this great airline everyone in LA talked about (called PSA) would one day have scheduled service. That, or Air Cal. But neither did. It just felt like rejection, and it made me sad. Even sadder when everyone else was growing, but not us.