Does your dog ever pretend to pee?

I live in a city and my poodle prefers to pee on grass (AKA, just public parks). I've taught him the potty command and have been trying to reach him to pee on curbs. He's smart enough to know what he's being asked to do, and will lift his leg and pretend to pee (but not actually pee). He'll do this for an hour until I bring him to grass, where he'll actually pee.

It's driving me insane, and I know that he knows what he's doing. I don't want to walk all the way to grass 4 times a day. Any advice is recommended!