2016 Avalon Hybrid backup camera and distances

The manual states the red proximity line is 1.5 ft measured from bumper.
When I measure the new car it was 1.5 ft. Now, 10 mo later, it is 4". Now Toyota tells me that is correct if measured parallel to the ground from bumper but what they really mean is 1.5ft from curbs, base of lamp post, etc. So, backing up into the garage wall the car will be 4" when the red line is reached. Or, in a parking space the bumper of the car behind will be 4". That is rather close.
Anyone measure the 1.5 ft from bumper parallel to ground, not angled down?
Very frustrating.
Thanks,
Charles