To add my own experience, I routinely ask on all airlines if I ever order steaks/beef fillet and except on a couple of Middle Eastern airlines on which I was refused due to health worries ;but they overcook meat less anyway) I’ve never had refusal in principle. How well it’s done in practice is a bit less consistent but there is usually some effort. On the ba forum, someone posted very specific instructions about length which he gives crews and the results look great but I’ll admit I do t feel comfortable doing that myself as I don’t want crew to feel micro managed. My best steak experiences have usually been on KE and JL where cooking instruction is often invited (“how would you like it?”) and delivery usually impressive.