All that goes on there is an evaporating tray of water and wet bulb temperature sensors (finicky to measure accurately). Imagine an environment similar to a dishwasher or rather, a sauna, where you play not just with the temperature but also the humidity by controlling the steam bath.
The Chinese commercial ones I am referring to use a fill valve with a float (not dissimilar to a toilet tank) to replenish the water from the evaporating tray found at the bottom of the oven. So might get away with an analog circuit.. I digress..
Instead of keeping your food in a plastic bag and recirculating the water through a heating element to keep the temperature you are just constantly boiling water and releasing steam so the entire oven cavity settles at an exact temperature AND humidity level. Hope I didn't bungle that explanation too much.
Anyway GM probably has super fancy home ovens of this nature for $10,000 a premium home gamer version of the sort of thing restaurants/fancy-hotels use. The pros simply front load food trays into them like this: https://www.youtube.com/watch?v=3cfll7tUcuA
https://www.youtube.com/watch?v=AJb9cYXo-4g
The Anova thing is basically a tiny toy version of that.
No bags, humidity control, replaces everything. Immersion circulators, therma-pens, toaster ovens, microwaves, dishwashers - it won't wash your dishes after you make the salmon in it but it will self clean. :)