Tank tracks have problems at a small scale that aren't immediately apparent at full scale. The big one - especially for something "in the dirt" - is dirt/mud g

Tank tracks have problems at a small scale that aren't immediately apparent at full scale. The big one - especially for something "in the dirt" - is dirt/mud getting between the tracks and ground wheels/idlers. This can easily stop the drive system, requiring user maintenance. Then there's the issue with water rusting parts (shafts, screws, etc). Also, more moving parts equal more things to break. Finally, on a small scale, tracks have a tendency to be easily "thrown" from the wheels depending on how turning is accomplished and the terrain. On a full sized tank or bulldozer, tracks still have these issues, but in the case of dirt, it can just power through the obstacles; dirt and mud may build up, and cause some rust, but the important bits are kept constantly lubricated. Any parts that do grind up the dirt just wear down instead of stopping (and eventually need replacement - very $$$$ replacement). If anyone cares to, hosing off the tracks with a water truck can also be done, but isn't likely to be done. Again, it all comes down to maintenance. Also, full scale tracked vehicles rarely turn "en point", because their tracks can be thrown just as easily as on the smaller scale, but cause more damage and more repair $$$ needed to fix/replace (plus doing it in the field isn't easy, either). The proper way to turn such a vehicle is to not perform such maneuvers, or if you have to, make sure you're on relatively flat and soft ground (that you don't mind utterly destroying - beware your wife's rose garden), and do it fairly slowly. The side load on the tracks and idlers will still be just as high, but throwing the track isn't as great. Usually, though, you steer in a curve just like a car, except using differential speeds on each track. There will still be side loads and "skidding", but the loads are much, much less (also, this is why such machines, whether tracked or wheeled, are known as "skid steered" or "differential steering").