So, in addition to all of the oddities I found with wild megalodons, here's the real cherry on top: Taming them is a piece of piss. A bit of training and they're more obedient than the family dog.
Now, I've heard of sharks getting very rudimentary training over a year or so, but not to this extent. Certainly not so easily. Sharks aren't mammals or even avians, they're fish. They rely more on instinct, or to put it simply, they're not very smart. You shouldn't be able to ride one like a jet ski.
I'm trying to keep an open mind like Rockwell suggested, but this just feels wrong.