The thing is, what we think of as "standard" service is actually super amazing service, compared to some places that don't have much of a tipping culture. For example in some areas you're not going to get any automatic check-ins, all you ever get is a response to flagging someone down.

So even when you think "standard" in the sense that nothing went wrong, it's actually wonderful that you didn't have to flag someone down, and therefore at least 18%. More like 20% if something made you think "that was nice." And this is coming from someone who has no problem dipping to 16% when mistakes are made (where primary responsibility is with the server) that aren't neutralized somehow.