Also I fail to see the distinction between an ESTA/ETIAS and a visa. If I need to apply ahead of travelling, and pay a fee, and this may be denied, how is that not a visa?
That is not true of schemes like ESTA or ETIAS.
Some countries have visa-on-arrival schemes, which are the opposite of ESTA and ETIAS. The visa still exists as a formality (maybe due to reciprocity or as a tourist tax), but you need to do little beyond paying the fee to get one.
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.