1. after code review etc. a change is merged to master 2. the CI tests are automatically run 3. IFF the tests pass the change is auto-deployed to staging 4. promoting a deploy to production is a push-button or a CLI command 5. adding 3rd party services such as New Relic / DataDog / Papertrail / Bugsnag is a push button or single CLI command 6. even things like upgrading to a new version of Postgres is distilled down to a few CLI commands
I think Heroku is not alone in providing this level of ease, but that's what I've been using.
I would argue that there is not a "gap" but there is actually "a thing that you can totally have if you're willing to pay more money and give up some customization or control," which makes it roughly analogous to the iPhone.