Reliability is a thing that grows, like a plant. You start out with a new system or piece of software. It's fragile, small, weak. It is threatened by competing things and literal bugs and weather and the soil it's grown in and more. It needs constant care. Over time it grows stronger, and can eventually fend for itself pretty well. Sometimes you get lucky and it just grows fine by itself. And sometimes 50 different things conspire to kill it. But you have to be there monitoring it, finding the problems, learning how to prevent them. Every garden is a little different.
It doesn't matter what a company like Fly does technology wise. It takes time and care and churning. Eventually they will be reliable. But the initial process takes a while. And every new piece of tech they throw in is another plant in the garden.
So the good news is, they can become really reliable. But the bad news is, it doesn't come fast, and the more new plants they put in the ground, the more concerns there are to address before the garden is self sustaining.