Saw this topic a few times and wanted to share my thoughts.
Self checkout can increase accessibility. People who have social anxiety, agoraphobia, panic disorder, autism, etc benefit from having the option to avoid forced social interactions. Stores often have their self checkouts arranged in a more open layout so people in wheelchairs, crutches, and other medical equipment may have more space to maneuver around than in the more narrow isles of cashiers.
It also has an element of privacy. A young girl buying her first tampons or pads, an elderly man needing to buy adult diapers, a young woman buying condoms, a non-binary person buying personal hygiene and clothing items that make them feel more comfortable with themselves, a Trans woman buying makeup, a single college student buying pregnancy tests, on and on. Self checkout means being a bit more free and comfortable to buy what they want or need without as much fear and anxiety of getting judged, verbally abused, drawing shitty comments, etc.
Some argue that it's wage theft or it's an example of losing jobs to automation. Yet I still see plenty of cashiers in stores with self checkout. Generally speaking (at least from my personal experience), self checkout has an item limit of around 15 items. Any more than that means you have to go to the cashier lines. There's pros and cons to both but I don't think having both is entirely a bad thing.