Why should it be impossible to learn.Any language can be learnt if you want to.You have to have the willingness,the enthusiasm,and the patience to get over the starting hurdles of sounding strange when you try to make conversation and you have to like the country
Many of the drivers on here have learnt other languages due to different circumstances,i.e.living and\or working in another country,or romance.
Obviously some languages are more easy than others.I found Dutch and Swedish easier than French or Dari but managed to learn them all so it is possible.