I suspect they probably thought the couple would have a somewhat more realistic view of how others would perceive them and use some filters to tone down their normal behaviour when they knew they were on TV, as most of us probably would... only to find that this did not in fact happen.

Yes. The couple seem to have no idea how they look to other people. I'd assume most chefs and restaurant owners know that verbally abusing customers to their faces looks bad to potential customers (and is bad for repeat business).