Well Houston is famous for no zoning, so how would that work?
Houston has zones... They just allow any type of activity in any type of zone. My assumption is that as long as commercial business occupancy is legally allowed to operate within the zone, then Apple is okay with it. The goal is to ensure that the repair shops are operating as legitimate commercial entities in an authorized commercial or limited commercial zoned establishment. They won't be signing up guys and ladies working out of their (or their mom's) basement.