this one costs around US$15. me and many millions of consumers in india use devices costing around this $12-$20 priced induction cookers because that's the only thing being available...
everyone has a soft button interface which sucks but because of the relatively cheap capital cost, you are able to buy a new one if the old one breaks. with good care i've used a machine not different from above for 4-5 years nonstop
I just really want at least one inexpensive unit like the one you linked to come out with a knob for temperature control. Surely that wouldn't affect the cost that much?
Unfortunately, there are some types of cuisine that rely more heavily on quick, precise temperature control.
I myselr used to have one that would go in 200W steps, that was also pretty great. Also never saw that on another model.
The biggest issue I've seen with consumer induction cooktops is that all the affordable ones use stop touch/tap interfaces that make it really difficult to adjust heat while cooking.
If the primary input was just a potentiometer (or rotary encoder, if they wanted to be fancy) it would be trivially easy to set or adjust any hob at any time.