Do You See the Sign?

A sign is to be seen. I, 5'3 tall, can see seven(7) unrepeated signs in the above picture while I am standing in this lavatory on a US Airways plane.

However, if I bend down at least 45 degree, I saw another squarish sign, warning what can be and can not be thrown in the trash bin.

Let's imagine our experience of taking a lavatory break on an airplane and possible activity routine there. We either want to quickly finish our job (sitting on the toilet facing towards the door or standing against the door) and wash up your hand or refresh yourself by toothbrushing, face washing or doing makingup using the mirror.

Chances are if you are not observant enough, the sign wouldn't be seen even when you are sitting on the toilet seat. Wouldn't agree?

Then, my question is: the sign is designed for whom to see?
for Kids, you may say, of age ranging 1-7 whose height may fulfill the requirement to see the sign. I may buy your answer. However, in real life, we observe that kids of 1-7 are normally under parents' companion to take the lavatory break and they normally do what an adult guides them to do.
If my reason stands, shouldn't this sign be designed mainly for users of teens or older? Thus, the human factor issues for the sign design should be reconsidered.