Knowing the towing companies out there, I truly wouldn't put it past them to tow any car. I kind of doubt they look too closely honestly especially on a dark and stormy night. If the dogs were on the floor sleeping, etc or a child was sleeping a car seat, I could see them missing it. Glad my state protects both pets and kids and has laws against endangering animals and children by leaving them unattended in cars (whether hot/cold/stormy/dark, etc).
I didn't go deep into this citation, but it seems that CA also has a law on that "As a result, it is illegal to leave a pet unattended in a motor vehicle under California Penal Code Section 597.7 PC."