No one is saying it's a large family. It is certainly a small family, but it seems to be very active and very wealthy also. To say it's almost defunct seems more like a fantasy than anything else. The lack of cases doesn't mean the family isn't active. How many westside guys never get indicted? Some of those guys have a ton of guys under them. They're not active? We also need to remember the state of the FBI these days. This isn't exactly their top priority.
The difference is, you can go back and see A TON of cases against the Genovese family over the years up to the present. You can't say the same thing for Detroit. In fact, while you admit there is a lack of cases, you also claim the family seems to be "very active." What the heck are you basing that on if not cases?
Furthermore, I've already addressed the "FBI has better things to do" excuse. Why do we see the feds and state law enforcement going after the handful of other small families remaining but not so much Detroit? While there has been some relatively minor stuff here and there, the last big bust (by Detroit standards anyway) was a decade ago now in 2006. And that was basically just a gambling case. The last really significant case was 20 years ago in 1996 - the GamTax case.
The Detroit mob isn't a big priority for the feds, or even local law enforcement apparently, is because what's left of it is very small (likely nothing close to the charts that keep getting posted) and primarily involved in bookmaking.
