Very good point - particulary as the crash was in the middle of a field, that appears to be muddy.
We haven't had much rain here in the last few days but this is reclaimed land lying (at the point of the crash) some 10 feet below sea level. The soil is thick sea clay - the type that stays wet-ish for a long time and sticks in big clumps to your feet when you walk on it. Also, the ground water level sits just a few feet below the surface so water is sucked up and, unless you have a tracked or four-wheel-drive vehicle, or a tractor, it's virtually impossible to drive any kind of vehicle on these kinds of fields.
A four-wheel-drive fire truck might just be able to reach the wreck but would have serious trouble getting away after standing still for more than half an hour. A regular ambulance has no chance at all. Schiphol has something like nine "E-one"s (8-wheelers) which should work in these kinds of fields.
The pictures of body bags being loaded onto a flatbed trailer towed by a tractor may have been ghastly, but it was probably the only way of getting them out of the field, short of carrying them by hand for a few hundred meters to the nearest road.
The tracked vehicle you see in the pictures is a Haglund. It is especially suitable for traversing all the ditches that lie around the airport. But from a book on Schiphol I have here, it seems that Schiphol owns only one.