There are 1.4 billion people in China. You’re showing me a couple of people doing who knows what in a clip of unknowable provenance. This is not the hill to die on, my man
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.