This is something that BA could fix very easily if they wanted to.

They cycle through a few destinations - I don't often have to look to see what the password is - I just try the usual suspects!

If BA wanted to prevent non lounge users from using their wi-fi, they could have more difficult passwords and change them frequently. It wouldn'y affect entitled users - they would have access to it in the lounge.

The fact that they don't shows how much BA care about bandwidth theft!