[pacbard]

Because applying for a visa takes money, time, and a visit to the embassy.

ESTA/ETIAS gets automatically approved within a few minutes of paying for the fee (I guess this is true for 99.999% of applicants).

Very few countries allow people to just show up and cross the border. US citizens had that privilege in a lot of places, but it looks like it’s changing now.

[ghaff]

I have never visited an embassy to get a visa--though I did cancel a couple of business trips when it became too much of an effort because of timing relative to other trips. I've travelled to a bunch of countries where I could just go through immigration with a US passport or maybe pay for a visa on arrival.

[sib]

Not true - there are plenty of countries that have e-visa (online application).