I have no quibble with people being denied entry for valid reasons, and although far from ideal, the circumstances of this woman's experience falls a little short of what I would call an "ordeal".
I do tend to object to them being manacled and thrown into detention centers with substandard conditions for weeks or disappeared to a prison in another country. It's that seemingly random possibility of draconian response that is so frightening. Not everyone will get it, but no one should.
You are, I think, referring to the case of Becky Burke, the British woman detained for 19 days over a visa issue before being deported home. I agree she was treated shamefully. My only point was that the musicians' experience, though very unpleasant, was nothing like that and sounds more like the result of their own carelessness in relying on the visa waiver scheme rather than on applying for the correct visa for performers on a short tour.
There's been plenty of publicity in the UK since Brexit of precisely this problem and how it affects British musicians hoping to play in Europe and vice versa, so they have very little excuse for not realising it might be an issue in the US too, since even before Trump US immigration and border security were well known to be pretty unpleasant.
A generation ago, even before the War on Terror, I had considerable first-hand experience of both US immigration and border control and their equivalents in the USSR. I always found the Soviet border police (a quasi-military formation, under KGB supervision) and the KGB a lot easier to deal with, and a lot more relaxed and humane, than their US counterparts.
