One of the big differences between an Internal and External mode game in the Anarchy Zone, is which characters drive the action. External games tend to be driven by the players - where they go in the zone and what gets done there is largely up to them. Conversely, are usually centered around Non-Player characters, with the player's being their agents or rivals. What might be considered safe is another inversion - External characters generally want to avoid city states, and Internal ones seek to avoid leaving.
Wandering the wastelands can be lucrative, interesting, and even fairly safe. Aside from the occasional battlefield or industrial accident due to the lack of human oversight or EMP - the land is actually not so much wasted as abandoned. So until they poke a hornet's nest of reanimates, pick a fight with raiders, or become embroiled in city-state politics - players are quite free to wander the Zone for their own goals. Getting back to their home across the country, exploring the area like a new pioneer, or showing up to help the helpless like the lone ranger are all perfectly valid motivations. Recovering old documents, weapons, machinery, or medical supplies can be big business. If one wishes to skip the middle man - gold and cash aren't too valuable, but the things they used to buy are available for the taking, just avoid some reanimates.
Of course, not everything is happy in the zone. Reanimates migrate about making areas less safe as time goes on. There is no ruin fairy happily restocking the canned goods in old houses - so supplies are going to run out sooner rather than later. Raiders or aliens might decide to take over the area, and city-states are always looking for outsiders to do their dirty work or blame for their ills.
Characters in an internal game usually start off content, but the trick is keeping it that way. From the beginning they have a home, more possessions than what just fits in a backpack, and possibly even a family (either all surviving, or a new one started after The Event). However, it takes a lot more effort to maintain a state than a little group of survivors, and many states are run by the people who took charge because they wanted to, not because they were qualified. Player need to hold some sort of job to keep their stuff, and may well experience first hand the power struggles that keep the city moving. Perhaps they act against someone to help maintain the status quo - or to avoid being evicted by the old leader.
Internal games run closer to the traditional concepts of a zombie game - struggling against others, with the threat of the hungry dead beyond the walls. Rather than an incidental problem when exploring, or a reason to leave an area rather than be too comfortable - reanimates are the wolves at the door and a constant danger to be avoided - by engaging in back hand dealings or other services for the community.