There is life beyond the seals, but it is frowned upon. The planet is still recovering and its systems are incredibly fragile at this point. Some people have left the stacks, preferring to live in the wilds of Earth as our ancestors did, but they are despised by most inside and life outside is hard. The seals were raised to protect the planet from us, as the planet sought to shrug us off. That these people choose to live without modern recycling of air and waste and continue poisoning this planet is a serious accusation. The acid rain and prevalence of large-territory, aggressive omnivores are strong disincentives as well.
Instead they excrete into the earth like the animals they hunt and eat. For the most part these groups are non-participants in the global economy, except for the outright black-market items they provide. These items include wild caught meat (an illegal and rare delicacy upstack) as well as other expensive endeavors such as hunting trips. Their services are not just for the upper-crust, providing off-list landing ports for smugglers of these goods and people. The sex trade within the cities has gone largely legitimate, so the market outside has been left to cater to the truly absurd or obscene.
Outside communities are largely ignored by the SuperCities, but there is little active animosity. Their populations and outputs are so insignificantly small compared to the industrial scale Chitroit and the like are capable of that they are not factors in global decision making. There has been, on occasion, raiding of supply and trade ships by Outside establishments. Banditry and piracy are common headlines, but that does not deter trade.
Living in the wilds does have its risks though. The profound and cataclysmic changes our presence forced the world’s ecosystems’ into have brought strange life to the forefront. The creatures that live outside must survive in a low-light and low-oxygen environment with vicious acid rain as a constant threat. This has given rise to an increase in predation as plant life has diminished. Most organisms have some form of defense mechanism, almost all designed against humans. Many creatures had even begun the transition towards hunting humans, as we became the most abundant calorie-rich substance in their shrinking environs.