Farmers use tractor to flow their land in time for the planting of their seedling. Without it, they won't be able to do anything on their land and they wouldn't earn money. Actually, they use their tractor not just flow their land, but also use as a mode of transportation for delivering their produce to the market. They wouldn't buy another vehicle for something that their tractor could do. Farmers use every last bit of money for their seedlings, and for their needs. There are times, when they use their tractor to where they want to go since in most cases, there are no other mode of transportation that is available for them.
However, the said uses of tractors aren't mentioned in this game. In this game, you would drive a tractor in a race. Like in any race, you would need to win it to win the game. You need to be first place all the time or you loses the game. Every third level, you would unlock a different tractor, which you can use in the game. Expect things to get harder as you make some progress. The road that you would need to drive your tractor to isn't a typical road that you see everyday.