I’ve always assumed that tips are for any non-professional personal service where the output quality can vary massively depending on care and/or attention to detail, and which requires a degree of trust in the service provider — whether or not there’s actually “table service” involved, or a human being directly handling your money. Tipping is effective at encouraging that care and attention to detail, and shows a deg…
I think the opposite is true. I've had better service in the UK and New Zealand and pretty much any country that doesn't have US tipping culture.
I could see it being true for high-end restaurants and offerings though, maybe.