I always see complaints about recaptcha like this, but I've never experienced this struggle, certainly not to such a degree as to be outright frustrating. It's always seemed pretty obvious to me what the right answers are. My personal take to your examples are that that a traffic light's pole is not a traffic light, but any part of the box that contains the lamps/leds is (even if facing away from the camera), and that neither large trucks nor buses are cars, but would include vans, pickups, and SUVs.

Hopefully these rules of thumb will help someone reading this find these captchas less frustrating.