> Nah, citizens of most first world countries don't need a visa to enter the US if they're visiting for less than 90 days.

That's true, though the Trump Administration has tightened rules for the Visa Waiver Program last year, after floating the idea that they might seek to end it entirely.

So, I think it's perfectly valid to see this as part of a broad policy of making the US less welcome to visitors and immigrants in general, though that policy is also more intensely focussed on repelling immigrants and visitors from non-first-world (or, in the language of our President, “shithole”) countries.

> You can just get on a plane and fly over.

Not quite - you will need an ESTA - a visa waiver, and the airlines (usually) check before you board that you have a current one.

But they are valid for two years, and trivial to get via the webapp.

True but the ESTA application has been asking for social media accounts for some time already. I was definitely surprised to see them explicitly asking me for my github account. Luckily it’s optional right now and I got approved without giving anything, but now the infrastructure is there and they only need to flip the required bit.