In authoritarian countries, sports have long been an important tool for laundering their international image. East Germany had a particularly notorious government-run doping program (with horrible long-term health consequences), and the Russian system is well-documented too. Talented young athletes, often while still children, are coerced into doping, with the full backing of security services, which use all available resources to manipulate the subjects and cover up any traces. I can't think of any Western country ever placing such emphasis on professional sports. That's definitely a factor too.
If you haven't seen it, I recommend watching Icarus, an exceptional documentary on state-sponsored doping: https://www.imdb.com/title/tt6333060/