Laws such as this are extremely common. They normally apply, as the Washington state law, only on public roadways and not on private property such as your driveway.
I recommend that if you ever do need to do this, as many people do on cold days, that you find your spare car key so that you can lock the car while it is warming up. That doesn't help the environmental aspect (pollution, wasting fuel) but it does take care of the safety aspect.
Which reminds me of the time that I had a dead battery.
I stopped at a major intersection on the way to a customer because there was a serious accident. The accident did not involve me, but I did stick around to give a report to police as a witness. And then I couldn't leave because my battery was dead! One of the policemen was nice enough to give me a jump start.
Then I drove a significant distance to my first customer of the day. I thought my battery problem was a one-off (e.g., lights left on so battery was weak but after driving would be charged up). No, it wouldn't start...again. My customer gave me a jump-start. When I got to the second customer (very close to the first customer as I had deliberately scheduled them for the same day), I left my car running in the parking lot while I went inside to fix a computer. That's something I would never normally do, but I had a spare key so I was able to lock the car, and that was better than an almost certain need for yet another jump start.
Then I drove back towards home, pulled up in front of my local service station and asked them where to leave the car before I turned it off. I went home (nearby) and they replaced the battery.