Interesting. Still cheaper to go from US to UK and eventually Europe than the other way, it seems. 
Didn’t know they planned an ETA for Europe, but walls for movement of people, goods and services seems like something some want. In effect it will just be more expensive and difficult for everyone. 
Do you live in the U.S. or in Europe? I’m asking because this topic can look very different depending on the perspective. From the outside, it might seem hard to understand why Europe is trying to tighten immigration controls, but when you’re actually in the middle of it, it’s a whole different story.
But this is already a touchy subject, probably too touchy for this soft-cushion forum. So I’ll just leave it at that.
Maybe - but look at flights into Dublin airport. Rep of Ireland is part of the EU so NO ETA (UK) and the EU’s ETIAS isn’t going into effect until September. From Dublin crazy cheap flights to everywhere in Europe.
If you’re talking Ryanair, check the cost of baggage and their policies. Even cabin luggage stored in the bins has a cost.
I agree very cheap travel, we use them all the time, but be careful.