Most of the data predates Toyota, and many of those HQs are in the NW side where several cities intersect. The reason, I suspect, is that the article chooses to

Most of the data predates Toyota, and many of those HQs are in the NW side where several cities intersect. The reason, I suspect, is that the article chooses top 100 cities by population, so Plano squeezes in. It does not have a ton of apartments, but the ones it has, especially west, are expensive and fairly new. Most of the inhabitants, in my experience, are service industry to serve the otherwise (former?) highest income per household city, meaning many spend a large portion on rent. That's one theory... the other being it's just a few % points putting them up there and may be just the current multifamily real estate swing.