because at the moment they are driving at like 2km/h
They obviously don't. The speed for the Baggage tractor is 4m/s, which means 14.4 km/h.
and they take half a year to get to your plane which is unrealistic in my opinion compared to IRL.
They don't obviously take "half a year". They take what the real vehicle would take to reach a terminal at that speed. Of course, as with all the rest of the things in the sim that are realistically timed, but might be boring to do, like flying over the ocean, you can always use Time Acceleration.
