I will re-iterate a suggestion I have made in the past. Document the spread between the W fare you pay and the best economy fare available by taking screenshots when you book. If/when you don't clear, request the difference from UA. If you do not get it, issue an FTC complaint based on the various justifications made in the "GPU lottery" debate. (opinions vary on likelihood of success - but I have not seen anyone try)

I did the above a few years ago and got certs for the difference which cut off my complaint route. Not likely you will get the same results today though....

I don't take my chances anymore, I only book when R available.