So having a different shaped can would mean you don't have to look at the label right?
What about checking the re-test dates? In the past whilst carrying out POL locker checks I've often discovered sections holding out date stock as still in use, indeed when I pointed this out cans of oil (some of which were out of date up to 12 months) were actually being used. To compound this one section at my last unit was found using OM15 that had been quarantined, even though they had been sent a memo advising them to return it as waste which they had returned signed and stamped as done.
Would a round tin stop out of date/quarantined product being used? No, it just makes it easier to carry on regardless of the state of the product held within.
I know, its terribly unhelpful of me to point out that there are far more things to look at on a can of oil than just what type it is before you use it.
Sorry, I feel we must agree to disagree on this matter. I'm obviously of the opinion that highly trained and well paid personnel should be able to read a simple label (which contains information important to flight safety other than just what the product is) whereas you seem to believe that shape saves all and bugger the age of the product within because that'd involve reading something, a task far beneath someone who is busy and they should be excused for not doing it.