Planetside is a very dynamic game, where normally borders aren’t defended all time, what makes it theoretically easy to pass enemy Territory directly. Never the less, you will always be confronted with disadvantages if you do so. Tank mines on the road, much higher probability to be confronted with enemy vehicles or aircrafts or armed enemy AV and AA turrets are just waiting for people to be careless and haughty.
There are much more reasons, why you should avoid unnecessary crossing of enemy controlled areas. Many points of this guide are based on exactly that assumption and try to help you to understand, why it is important to change your territory allocation in a sustainable way to receive that little benefit here and there, which most of the people don’t pay attention to.