Common sense is an useful tool. It helps us estimate outcomes when data is absent or scarce, even if it's frequently unreliable. When I leave my desk to go to the bathroom yet again, I expect it to be there. Can't prove it, but it's a reasonable assumption. Without it, every human action would require scientific studies and high quality measurements.
The way to contest common sense isn't to point out that common sense is often wrong; instead, it's to provide data. My assertion is that when going against a statement strongly rooted in common sense and, YOU are the one who has the burden of proof.
Yes, perhaps authoritarians would do a worse job at catching criminals if they were omniscient? I'm not saying that you ARE wrong, just that you are LIKELY wrong and thus you should provide data to support your claims.