I think it's the exact opposite of "users don't notice". I think it's more that people are annoyed but Uber can't measure that easily, so they don't realize. Anecdote: my friends and I have frequently experienced this recently and the result has just been frustration - "it said 3 minutes and now it says 10 minutes" or "why's he driving over there?!". I hang on for the Uber, but if there was a taxi driving by I probably would have hailed it.