My understanding is she refused treatment twice (both in the form of an ambulance ride to the hospital at the time of the incident, and later in the day). Once she started having the headaches, it was likely too late. It would not have mattered whether she was in Canada or the United States.
She also refused a helmut. Sonny Bono refused to wear a helmut because
he thought it looked dumb. I can understand why people don’t like them
but they do help of you have a bad spill. Also, the instructors did
try and make her get medical help and she refused. People are
often embarrassed to make a big deal out of a fall.
Supposedly the Canadians sent an ambulance to the ski resort slopes and she turned it down.
I think it was a tragic chain of events. She probably fell down, hit her head but not that hard. It was probably a minor accident and she brushed it off.
She probably thought she was fine. She may have had some medical issue where a minor accident would set it off. Very sad.