Are we talking about 1 BTC or a bitcoin equivalent to $100? And what age were the children? It seems to me that most of the people who know how to handle money know or have heard about bitcoin, and if they are asked such a question, it would be logical to clarify how much bitcoin costs now, even if they dont monitor its price.
If you watch the video, the two girls were offered to chose between $100 cash and 1 Bitcoin and the girls without hesitation chooses $100, lol they can easily search what Bitcoin is since connection to internet now a days is very easy and we can access information easily.
People who go to work every day and are not interested in finance and investment may not know the price of bitcoin, not know the price of gold, how much a barrel of oil costs, and this is normal. But a person who can think will find out this information if necessary, everyone has a smartphone and it will only take a few minutes of his time.
Not really, people who go to work every day have idle time where they can read newspapers, watch the news on tv or browse social media. With Bitcoin's name popping everywhere, I doubt all of them are ignorant about Bitcoin.