The home groundsman prepares the pitch if I am not wrong.
Also, I remember India toured South Africa and was given the slowest pitch in the country for the warm up game and then the fastest pitch in the first test match and they got skittled out for 100.
You dont get congenial pitches to get into form, get a lot of practise out in the middle in tours nowadays.
Ealier there were much more tour games. So the current teams do not get that much practise any way.
Face it it is TOUGH to win on tours, specially in alien conditions. Which is why it is always considered the bigger achievment winning abroad. Also, the teams which cope over these conditions become great.
Such is cricket.