With your example, why would Tesla advertise to you after you have already converted on a purchase? In fact, Tesla can use your email address on a negative aud

With your example, why would Tesla advertise to you after you have already converted on a purchase? In fact, Tesla can use your email address on a negative audience list when advertising on display networks that hit publishers like NYT. I wouldn't be surprised if Tesla was doing this to optimize their ad spend. For purchases where you are retargeted, that's because when you buy something, you're a magnitude more likely to purchase it again (i.e. as a gift, have a backup/travel one, etc.). Goods like automobiles are an exception here, unless you're in the business of buying multiple cars in the same month.