Obviously there are way more occurrences than this video. Also, the lady in the video acted like nothing was wrong and admitted no shame, which means there is a culture/common practice of using gutter oil.

Wikipedia says that today this carries the penalty of decades in prison and a suspended death sentence. I very much doubt it’s as prevalent a practice as you suggest. To suggest that this crime is a “normal part” of Chinese culture is simply wrong.

There was no penalty/death sentence for the recent public incident of the oil tank truck that was found transporting both toxic industrial oil and cooking oil, without cleaning in between. Which apparently was a wide-spread practice, as confirmed by netizens. Instead the officials just hand waved and said it's an isolated incident, and they're looking into it. And no news of it since.