Each Node (or LDL) is considered a Proxy who transmits data to the rest of the world. Proxies can limit incoming data so countries can ban certain sites/zones (like social media during revolts, or other political sensible content).
The problem is that proxies tend to log every visit ... and usually, netrunners don't want to be traced.
Each times a netrunner pass through a proxy without being logged on, he adds half the security value as a penalizer to his Initiative. So if he goes through:
Night City (T2 S2)
He would accumulate a trace value of 13 and a security value of 7 (-3 to Initiative).
Of course, you can buy a prepaid SIM card (10 to 30 credits) for your cyberdeck and throw it after the run making sure no one knows who you are. Just remember, if someone trace you - thanks to I-G algorithms - they know where you are in the Real Space.
So ... try to hack from a secure/anonymous place, will you?.