After reading many of the chains on spamlines, I have seen many differing opinions on spam lines and how to stop or compete with spam lines.
Some people compare them to Low Cost Carriers (LCCs), while this may be accurate to some extent, it is not completely accurate. The largest LCC (Southwest Airlines) has a fleet of 715 Boeing 737 variants with 249 on order. The largest spamlines have over 10000 aircraft, and almost every major type of aircraft too. There is no saying that competing with a spamline is like competing with a LCC.
Some say spamlines are a product of capitalism, they are not. They are a product of basic AI passengers who have no or very little regard to the airlines service and only care about the ticket pricing. They are also the product of the ways hubs can influence passengers amounts. No airline in the real world would be able to operate fully booked flights between two regional airports with widebody aircraft, or honestly anything larger than a regional jet. The fact that hubs essentially create more passengers gives spamlines a way to operate and be spamlines.
Spamlines are also easier to make because of the unrealistic amount of aircraft leasing, most airlines own some or most of their fleet, because leasing is uneconomical, but this is not the case in AE, lease prices would need to be raised in order to stop spamlines.
Many players are annoyed by spamlines and this issue needs to be fixed in order to create a realistic and competitive atmosphere in the games. Actually scheduling flights would be one way to deal with this issue, passengers would be more likely to take flights with shorter connection times and airlines could better utilize their aircraft, this would also repurpose hub usage. Passengers also need to be more influenced by service than price, this would include actually managing legroom, as the current way of configuring aircraft does not tell you how much legroom passengers have. Inflight service needs to be more valuable to passengers, one way to fix this is provide a more comprehensive breakdown of travelers, telling airlines what types of passengers are in the demand for a certain route, an example would be business travelers want their flights to match with their schedule which goes back to a previous point, people on vacation will want more service on their flight and may be willing to pay a bit extra, while some people who just need to get somewhere may choose the best price to a reasonable extent. Another thing to add would be more realistic delays, which could influence passengers, an example in the US is Spirit Airlines who is late and delayed quite often, compared to Southwest or Delta, who are on time a majority of the time.
One thing to think about is that if you saw an airline in the real world that sold tickets for $1, you would either know that its too good to be true, or that something is very wrong with that airline, such as their safety might be way below par, or they might not take you where they say. You would know something sketchy is going on, and you probably wouldn't fly with them.
Spamlines are not the product of anything but a game that needs major adjustments in order to create a feeling of realism.
(No one should complain about spamlines in sandbox worlds because that is literally what those worlds are made for)