Onelight is solely responsible for repurposing the old Network into the inter-city infrastructure it is now. Despite their name, their employment isn’t simply focused on software development, management, and encryption, they also design hardware and extendable, computerized machinery. Each corporation is inclined to have their own hardware and software teams, but they cannot violate Onelight patents, so Onelight still sees lots of work from various different corporations and groups, and if their teams are competent enough, still have to pay royalties to use Onelight protocols1.
Software isn’t necessarily an esoteric thing in the City, but if you’re good with Terminals, why not join Onelight and get paid for it? It’s additionally one of the nicer corps.
You are safe from many things in the Cities, but copyright isn’t one of them.