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.
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.