I don't know if it's so much of a lack of desire to compete as it is an allocation of scarce resources. UA just doesn't have enough narrowbodies with lie flats (i.e. 752s) to throw around on transcons when they are still also really needed on the thinner Atlantic and Hawaii routes from a performance perspective. Plus, as I mentioned earlier, the heavily delayed MAX 10s set a lot of plans back. UA could probably sell lie-flat seats profitably on a lot more routes than they currently have aircraft for.

If UA really does end up taking delivery of ~100 or so A321s with lie-flats like what we think will happen (including the CFM A321s and XLRs), then I think it's very possible we'll see lie flats on SFO/LAX-BOS, IAD-SFO, EWR-SEA, and all kinds of other transcons. But NYC-SFO/LAX and transatlantic will always take priority.