I mean the megalodon specifically - likely a much bigger population lived in the Atlantic than the Pacific.

I think miscellaneous shark teeth are the most common fossil at Sharktooth Hill, they're just not as big or interesting as the megalodon teeth because they're difficult for a layman to age. Most megalodon teeth are obvious due to their size and most people are happy with a 5-25 Mya estimate.

also presumably because shark teeth are exciting

I bet the name is because is because shark tooth is what somebody can recognise better. "Is this a seal or a fox skull?"