Not only were the shops shut on Boxing Day, January Sales literally didn't start until January. Sales starting between Xmas and New year is a relatively new thing (approximating 'relatively' to be within 15-20 years or so).Ok, I could be wrong here but Emma said in the vlog that she has been going to the boxing day sales with her Mom since she was a little girl. I'm 6 years younger than Emma and I'm sure (though as I said, I could be wrong) that when I was little the shops were closed on Boxing Day.
Edited to add that I've just seen the post where someone looked it up and it was late 90's so I wasn't too far out.