Living on top of each other, especially in childhood & adolescence, combined with other environmental and health factors explains almost all of it. If you’re malnourished and your immune system is in bad shape, you’re at risk. If you have HIV, you’re at risk and so on.
Unhealthy people are more vulnerable to TB, absolutely. Infections in general are more prevalent in people who are underfed, or living in bad conditions. Other risk factors are exactly what you would expect: smoking, drinking, bad fitness level, and being young or old.
TB rates are basically a function of 1. how immune compromised your population is, and 2. How much access to healthcare there is in the country (poverty, basically).
[1] https://www.longbeach.gov/press-releases/official-city-of-lo...
A proper study [1] shows mean infection rate of ~20% in the worst regions (Far East and North) with the highest rate up to 47%. The situation should be better in the western regions. For comparison, in the US studies show ~4% infection rate [2], so situation in Russia is relatively bad, but improves steadily since 90s and it's far from being catastrophic as the 80% number paints it.
[1]: https://www.tibl-journal.com/jour/article/view/1706
[2]: https://www.cdc.gov/tb/hcp/clinical-overview/latent-tubercul...
All children and professionals working with children are receiving yearly TB testing ("Mantoux test"). Prisons used to be a major vector, but that was reduced by doing TB prevention (antibiotics).
Nobody likes getting TB.
I’m no expert but I also suspect access to medical care is also a big part, as typically only active cases spread the disease. If you are symptomatic and get some antibiotics, you might not spread it to very many people. If you’re symptomatic and go without treatment for ages, then you might spread it to loads of other people.
As we learned during covid, small differences in R value massively change the prevalence over time.