Some people say vwap is easy/simple, when they really mean it’s well-researched. They mean other benchmarks are lesser-known and more sexy. Actually, implementing algos to beat the vwap benchmark is not easy at all.
Some people say standard option pricing model (BS) is trivial. They basically refer to those fancy models like stoch vol etc. I think this is jargon arms race — “who knows the most jargon”. I feel the intricacies of BS model is well-researched but not simple. Is theory of relativity simple?
Some people say vanilla derivatives are simple (cf exotics). well, lots of publications, but many unsolved problems and unanswered questions.
some people say STL is simple. They probably refer to the fancier containers. I feel STL has lot of details we don’t understand.
Some people say java generics (and c#) is simple. They mean compared to c++. But still there are many design tradeoff and implementation details we don’t understand.