I don't think it is entirely true that RQ is based on random selection. I recently got a finger print request and my facts seem similar to yours. I did a multiple US/Canada zip code crossing for a day trip in the last 4 years.
Huge, huge difference between a mere Finger Print request and the subject of this thread, primarily PPQ-QAE CIT 0205 and related requests, among which a FP request is just one, the easiest one except for signing and submitting a consent for IRCC to directly access the applicant's U.S. travel history through government sharing arrangements.
The cover correspondence from IRCC, which is accompanied by the CIT 0205 Physical Presence Questionnaire itself and other requests, explicitly states that it is RANDOM. However, there are indeed some reasons to suspect it is, at the least, not entirely random.
To the extent your facts are similar to those of someone who was issued the PPQ, and you have NOT been issued PPQ, might actually evidence the PPQ is random. However, the odds are high that your facts and circumstances differ in a variety of ways so not withstanding some similarities, they probably are not similar enough to draw conclusions based on you NOT getting PPQ and someone else getting it.
With some exceptions, the questionnaires applicants have been receiving recently are the CIT 0205 PPQ-QAE. NOT RQ. Even though some of those who initially reported the "random questionnaire" for "quality assurance" referred to it as "RQ," these were actually the CIT 0205 PPQ-QAE.
So far it appears the CIT 0205 PPQ-QAE is issued to applicants prior to being scheduled for the test and interview. Recent RQs, in contrast, appear to have been issued at or after the test/interview. However, reports of RQ these days are so sporadic it is not clear that that procedure is still being employed as such . . . perhaps replaced by the PPQ procedure, or "exercise" as IRCC refers to it.
I got finger print request and test invitation the same day.
Likewise, huge difference. Fortunately not anywhere near as many are reporting PPQ as the number who report getting a Finger Print request. A FP request is way, way easier and less likely to cause problems than the PPQ, which is profoundly intrusive, requires the applicant to provide a broad range of documents showing proof of where the applicant lived, where the applicant worked, what business activities the applicant has been involved in, how often the applicant obtained provincial health care, and most are required to have a Canadian citizen reference who can attest to the applicant's life in Canada, including where the applicant lived and worked, and the applicant's social life for at least two years.