Saw a dog in a car

In Dallas, hot and sunny and some frick leaves his dog in his car. I was in an area with a ton of shops so there is no way of knowing where the owner was to go find him. I went up to the car but the window was not rolled down. I thought about breaking his window but I was afraid the dog would try and get out and hurt himself.
In the end I wrote down his license plate and will report the guy, but it's ducked up there isn't someone to all in this situation to come immediately.
I felt helpless and terrible for the dog but didn't know what to do. I couldn't wait for the guy to come out and call him out on it bc I was late for work, plus that isn't going to help the dog but wtf.

Poor dog