As an Australian I can comment on this, theres this wonderful thing called "Context"
At McDonalds they refer to them as fries, but if you ask for a large chips, they know what you mean. If you go into a petrol station and ask where the crisps are, nobodies head explodes. If you go into a place that has ALL 3 (french fries, chips and crisps) and say "Can I get some chips" the person will ask for clarificaton.
British roots and American television has made OUR english quite flexible.
As a rule most people I know think of french fries or fries as thin cut and chips as thick cut. Most restaraunts only do one or the other. If you ask for steak and chips and they do fries, they will either clarify for you (more likely) or just bring you fries.
Context and qualifying information. All 3 are considered "chips" like a baguette, a hot dog bun and a regular sandwich loaf are all "bread"
Nobody asks for steak and chips expecting a packet of potato chips next to a plate with just a steak on it. People usually ask for "A packet of salt and vinegar chips please" they dont just shout "CHIPS!" at someone expecting them to figure shit out. If I were to send a child to the shop I would give specific information. "A Big bag of plain chips" or "A large hot chips"
I think they're describing how fries and chips as fries are different. Thick cut (or steak cut) fries are chips, shoestring fries are fries, and US chips/UK crisps are crisps if they serve all 3.