Why not put "NON-ETOPS" on instead of ETOPS?
Wouldn't it be easier to spot a NON-ETOPS when doing a walkaround, than spot an ETOPS? It may trigger more in the brain than the absence of the word "ETOPS".
I think not, for two reasons.
1. Marking non-ETOPS would not be fail-safe if the mark were omitted.
2. Very many people simply do not register negatives. If you were to stand up before a group of people and say "The sky is not yellow," a significant proportion of them would swear blind you had told them the sky was yellow. It's so deep that the high level of intelligence required of flight crew wouldn't be a guarantee.