Correct, the binning is hard-coded in the kernel driver.
This would seem to be a major bug in the Mediatek driver, admittedly one which Planet could not have anticipated.
Supposedly, the point of the Samsung technology in these sensors is to bin pixels only in situations of low light, but the driver appears to bin pixels regardless of the level of illumination. I can confirm that this does happen even when shooting in very good light levels.
As noted elsewhere, the images also appear over-processed, as if there has been an excessive application of noise reduction.
Overall it seems as though the driver is permanently fixed in a mode heavily optimised for 'low light' photography.
None of this matters too much for low-res viewing of a full image on a 'phone screen, where these issues are not visible, but they do cause problems when cropping to a small area of the image ('digital zoom') or viewing on a large hi-resolution screen. Under these circumstances, for outdoor scenic photography in good light the results are awful when compared side-by-side to my battered 5 year-old 16MP Galaxy Note 4.
I find it hard to believe this is anything other than a driver problem, rather than a hardware problem with the sensor.