Do you know how many delivery services there are now. So many you wouldn't know if it was on the shirt. Postmates Doordash Grubhub Ubereats Instacart Seamless Waitr Even your Lyft and Uber guys can run up on you. There's tons more.
Yeah they are recognizable and actual employees. Most the others are 3rd party so they probably dont advertise. Hell most probably work for multiple.
I'd like a ride service like Uber but the driver has additional entertainment or value according to your preference: comedian, shrink, motivational speaker, preacher, cannabis dealer, bard/singer, prostitute, etc... wish me luck
Majority of cars I see out here with a participating driver, have both stickers. But like @tirk said, a lot of these drivers work for multiple services and at least in my area, many are teen drivers and can't afford, nor are they willing, to buy a shirt for every company.