For one, having a visa comes with a high chance of being admitted to the country (although never 100%).
That is not true of schemes like ESTA or ETIAS.
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.