They built the cul de sac yes its not real, some of the interior of carols home is also recreated on a sound stage but lots of filming is in the fake cul de sac.
Stop buying the lies about Vince being slow or that his process is slow, its bullshit.
He had written the first 2 episodes completed scripts before he showed it to rhea, the first person he told about the show, after she signed on he then shared it with his producer buddies and they started putting the show together. Season 2 is already written the whole arc of the show is already outlined and the story boards for all seasons 3-4/5 are already done. If they wanted to they could spend the next year filming seasons 2-5 and release a season annually or even every 6 months like clockwork.
They are pretending that they didnt write season 2 yet even though apple already ordered 2 seasons out the gate to excuse the delay between seasons which is intentional streaming fuckery