No, Mixpanel does not auto-capture user interactions. Heap does. (Disclaimer: I build Heap.)

The Heap approach (i.e. auto-capturing events) lets you run retroactive/on-the-fly analytics. Without it, this feature is closer to a mobile equivalent of Google Tag Manager's click listener tag (https://support.google.com/tagmanager/answer/3415369?hl=en#C...) or KISSMetrics' click tracker (http://support.kissmetrics.com/tutorial/event-library-tutori...).

Happy that Mixpanel is making their event-tracking easier, though. It's a major pain-point, especially for mobile apps.