Reasons for detainment in Xinjiang are vague by design
Because the rules for getting detained are so vague, it makes Uyghurs fear about doing normal things, not knowing what will or will not get them into trouble.
A central element of this campaign is uncertainty. It is difficult to judge which of these items are official policy and which are simply the result of ad hoc decisions made by local officials. This is likely by design. One Uighur interviewee told HRW how he simply stopped using his smartphone because he could not tell which websites were allowed and which might incriminate him; another described how she stopped talking to neighbors and strangers altogether because she did not want to unintentionally say something that might bring the police to her door. Vagueness breeds fear. Fear makes the people subject to the Communist Party’s campaigns easier to control.^[ 48 Ways to Get Sent to a Chinese Concentration Camp - ForeignPolicy]