Of course we can read labels
, but it is yet another "foolproof" failsafe to help prevent cross contamination. It is the same reason aircraft emergency systems are painted yellow and black, ie easy to identify quickly. Although its easy to say RTFL, it helps prevent a mishap in ****ty dark conditions, especially when you are doing a big job that involves engine oil and hydrulic oils being filled up, just like a herc K where the prop takes OM15 and the engine takes OX27
. These things have been developed over time for a reason, ususally because an accident has happened before
