Same exact product, different price?

We were at Target at my friend's hair dye was 9.99 in store and the EXACT same product was on the Target online store for 7.99.

The lady at the cash register said she couldn't price match on Black Friday weekend.

It wasn't even price matching, it was the original Target website. I just bought it anyways and went to costumer service and got my $2 back. The man there told me they have to honor it if it is the same product and on their original website.

Why wouldn't the original lady do it?