Adding to what PzKraut said... manufacturing tolerances for thermals is, from what I understand, insanely small before there's a noticeable decrease in quality.  The ability to mass produce to that tolerance is beyond Russian industrial capabilities.  Knowing this they don't even try, but instead go with a lower level of tech which is not only cheaper but also more inline with their industrial capabilities.  Or they purchase them Then there's reliability.  There's tons of cheap things you c