If only they could block them from entering at all…
Sadly, even the Lords could not block entrances at all, as the Elders had tried many times.
The reasoning was similar to why they couldn't require everyone who entered to take an oath, as if needing a visa to enter.
The System—for better or for worse—protected the right to survive. It was its main function and meaning, after all. It was why oaths, unless they were slaves, could not be extremely overbearing.
In the same vein, the system prohibited stopping people from entering the protection of a territory as long as they paid the entrance fees. There was also an entrance fee cap, limiting the abuse that lords could impose.
The designer, whoever they were, probably just wanted to protect as many people as possible from this world that was just dangerous by default.
Anyway, this meant that the 'bad guys' could enter as long as they paid, and would remain inside unless they were kicked out for doing something against the rules.
