Heathrow is a terrible example. Everybody flies into it, and it's the easiest place in the entire game to have huge profit margins, so if you want to start later in the game, as a smaller airline, there is absolutely no point to doing it at LHR. Same as RL, how many smaller airlines, or low cost airlines, have started up in Europe in the last 20 years? (I have no clue) How many of them started at LHR? (I'm tipping zero.)
If this sounds like me picking on you, I apologise. I'm going to have a quick look at what I can see of your two airlines. I'll just comment, hopefully constructively, on what I see.
In DOTM, you've started in AMS on day one of the game. You've started very slowly, with a pair of small, expensive to run Antonovs, and put them on short routes to the two huge nearby airports. Then you've grabbed 4 more of an entirely different 40 seat turboprop, and tied up a lot of your money in buying a 40 seat, very thirsty small jet. Plus a single jumbo, that by itself is enough to fill the route to Dubai, but competes against two other players offering similar. Again, think about RL. How many airlines run small turboprops out of AMS? Looking at the routes themselves, I can't see a single route that is beyond about 100% supply by a single player. But I see every route you fly having competition from multiple players, resulting in extremely low load factors. Which isn't surprising, because you're in one of the biggest airports in the world, and you're only flying to other big airports. There are empty or undersupplied routes you could be flying, like to Lille, Norwich, Leipzig, Liverpool, Bournemouth. AMS is running low on slots, but they are still available at almost any time of day. You've started in a huge airport, where costs are high and competition is fierce, and you're using small planes that don't generate much revenue, and expanded very slowly. If your aim is to run a domestic, shorthaul airline of turboprops and/or small jets, no worries, you can be very successful doing so. But you need to pick an appropriate airport to do it.
MT, you literally BKed as I was writing this post, so all I can see is you were in Dayton with 4 planes. Which is a much better choice for an airline of small planes.
It's very possible to grow quickly without cheating. By being aggressive, and by picking good routes. You got your two antonovs on day 1, waited a full month before ordering two f27s, then another 2 f27s over the next two months. So 4 months into the game, you had less than 300 seats making you money. On day 1 & 2, I got 2 planes and ordered 3 more. By the time those first two were delivered, I'd ordered two more batches of 3. A mix of 707 & 737. So one month in, I had 11 planes, well over 1000 seats, and more on the way. Which I could do with just the start-up cash. With that many planes, I already had revenue of 3-4 million/week, so at least 500k/week of profit. Which lets me order more planes, which increases profit, and it snowballs from there.