Oh, don't get me started on Ryanair, but alas. You go through what seems the entire check-in process, you get what seems like a summary at the end, with a link to a UK government site where you need to go next to get a travel authorization, I spend an hour doing that, finally finish that, I show up to the airport the next morning to be told I'm not checked in, having to pay a hefty fee to do a late check-in for each…
Followed the app's instructions to go to gate 15, sat there waiting for the gate to open, until eventually getting a notification that I'd missed the flight from gate 30. Went to the help desk, was told that since I was the only person who made that mistake it was clearly my fault rather than the app (which was still displaying the wrong gate, even while I was at the help desk). Got booked on a $400 replacement flight for a journey which was originally $50. In the queue to board the replacement flight, I meet around 20 other people who missed the same flight for the same reason, all being told "it's clearly your own fault, ryanair has no responsibility here"...