An explicit transfer date forces both sides to build for independence from day one, instead of drifting into an indefinite retainer where the agency quietly becomes permanent infrastructure. It changes the incentive: get paid to build something that works without you, not to stay indispensable.
In most GCC agency relationships the incentive runs the other way — the agency benefits from the client staying dependent. Kando's model flips that, which is also why clients typically know from the first call roughly when they'll own the engine outright.