The US, maybe. But wiki suggests ETIAS (the EU one) was proposed in 2016 whereas the UK ETA idea was created around 2023, so ETIAS can't be a reaction to ETA - perhaps the other way round?

I'm not sure if, without Brexit, the UK would have ended up with ETIAS anyway - it's a "mostly Schengen but not exactly" thing so it would have depended on what agreement they came to.

My impression was that the EU did it to prevent people doing visa-free layovers from claiming asylum, while the UK did it to negotiate a dual exception with the EU in the future.

ETA is a visa to the entire world in all but name. I'm not looking forward to the future where every county implements is and visa-free travel becomes a thing of the past.

Have you filled one out lately? The questions have got a bit wild.

oh no, basic border security!