Census: the estimated return rate of the last census was 97%, i.e. 3% of the population didn't give it back. That's millions of people even by the official numb

Census: the estimated return rate of the last census was 97%, i.e. 3% of the population didn't give it back. That's millions of people even by the official numbers. Yet there are only ever a few hundred people who get convicted for failure to complete the census. Meaning, the chances of anything bad happening to you for not filling out the census is on the order of 0.01%. That's a very weak incentive for honesty. If you're already living on the outskirts of the law (illegal immigrant, trafficked, etc), you can just ignore it, and it'll be about as risky as ignoring a TV license threat letter. The accuracy of the census depends on the bulk of the population's honesty and willingness to do this civic duty. Most people think "oh that's something you just have to do", like stopping for traffic lights on an empty road at 2am. It's an illusion, you can just ignore it. The census is meant to be the single source of truth from which all other population-related metrics are derived, but since it only comes around once every 10 years it's usually out of date. In practice you always need a bunch of fudge factors to account for population growth, immigration, emigration, people moving around, etc in the years since the last census was taken. And that's not even accounting for tourists and so on. I've seen how this sausage is made; you just get used to the idea that the census info is merely a rough guess that you have to finesse until the numbers look reasonable. Those fudge factors are themselves often taken from ONS projections. So if the ONS itself has a small systematic undercount because of an overly-optimistic methodology, that poisons all calculations downstream. As for the registers: the point in that thread is that the registers disagree with each other. Covid-era NHS patient counts, for example, because it's obviously in people's interest to get healthcare in the way it isn't to fill out a census form. EU settlement applications is another one. Surveillance cameras: do you know what the "CC" in "CCTV" means? It's not all fed into a giant database. There's nobody combing through all that video and counting how many people are there. In almost all cases the data is retained for a few days and then gets destroyed with no human eye ever looking at them. For all the talk of mass surveillance, there is still an enormous world that lives hidden outside the notice of the state. You only see the outlines of it during unusual events like Covid or Grenfell, like a lightning bolt suddenly illuminating the landscape for a split second. There were dozens and dozens of people living in that tower that the local authority had no idea existed. We only know about it because it went up in flames -- it can't be unique.