To some degree, that is intentional, and we have a word for that: dishonesy.
English words also have established meanings.
There is a basic rule in language, which is don't overload words in a confusing way. Breaking this rule is never excusable.
If we were on an economics board, I would not complain about this, but well, we're not.
They have no such thing. Grab a decent dictionary and start looking up random words. Many have at least 2 or 3 different definitions, often unrelated and sometimes even contradictory.
Are mathematicians dishonest as well when they use phrases like "almost everywhere" or computer scientist when they describe a problem as "Hard" or ballet dancers talk about an "adagio"? All those words have very specific generally understood meanings in the field which might confuse someone with no background in the field.
What alternative to you propose? That they make up new words each time they want a short hand to describe a specific concept, or that they use always a long descriptive phrase each time they want to talk about these concepts?
2) Jargon. Don't tell me that software development doesn't have weird uses and definitions of words. Meanings of words changes over time, languages aren't static. The term efficiency in the context of economics is rather well established and part of the English language, despite what you may personally think about it.