Just Failed The CDL Exam When Not Turning To The Right On The Green Light On A Tight Turn

I am curious what you guys and girls think about this one. I just failed a CDL exam in a little Californian town. I was taught by my instructors to impede two lanes when approaching this tight turn to the right. According to the instructors, I had to announce to DMV that I am going to impede two lanes, then I could proceed and impede two lanes to the right, if there was no traffic there... apparently, if there WAS traffic there, I was supposed to proceed on green, because *APPARENTLY* the turn was very tight but not undoable. So, during my test I told the examiner that for safety reasons I'll impede the two lanes so I'll have to wait till the cars on the right coming the opposite way clear... And I already impeded two lanes when approaching my tight turn... so by waiting for the cars in the opposite direction on the right turn to clear I missed the green light. Then I waited until the opposite lanes were cleared for me to impede when turning right. She failed me just for that.

However, my driving school instructors said that there is another tight turn in this little California town when it's OK to impede two lanes when turning right and then impede the lanes of the opposite traffic when turning right! And to wait if there are cars there... and wait on green light. So in this case I could have waited even on the green light and waited until the opposite lanes on the right for my right turn are clear... How come in two very similar situations in one case I could wait for the traffic to clear and in another case I was failed because I stopped on green when doing the right turn (but announced to the DMV examiner that it's for safety reasons)?

The DMV examiner said that she had seen other students from my truck driving school go through that tight turn without impeding the traffic, even when there were cars there... Isn't it a judgement call when the turn to the right is very tight and sometimes you must wait until the traffic in the opposite lanes clear. I thought that I was doing this "for safety reasons," but she mercilessly failed me.

To me, these two situations with two tight turns on two different streets, where in one case you can wait until the traffic clears, and in another case you can't wait until the traffic clears and can proceed sound very strange. How is this "the law"? It's a judgement call, isn't it? Who is measuring these lanes? They both, these lanes on these two different streets, look very tight for my 53-feet tractor and trailer. 53 feet! It's a huge thing!!!

And apparently the DMV had already discussed what to impede and what not to impede with the driving school... This sounds very strange and subjective to me... any ideas? Am I totally in the wrong here?