I wonder if you've opted out of promotional emails from them in the past? Do you still have the app installed on the same phone you used as a driver?
As a consumer I get push notifications and emails from them every week if I haven't ordered food in a while with new deals, etc. I would strongly suspect they're doing the same thing for drivers these past couple months and maybe they just don't have a way to reach you. If they aren't even doing that it would be truly bizarre, there are billions of dollars on the line and it's their entire business.