Bangladesh need to be banished to playing against Vatican City or Andorra. They are absolutely rooted. They have about as much mental toughness as a chicken. The difference between the two sides is that Zim want to win, they approach each test match wanting to win it even though they are often hopelessly outgunned. The bangles on the other hand still, after 12 years, have the mindset that improving bit by bit is enough. It's not good enough.
That said I'm glad Zim are doing very nicely.