Cause they can smell each other apparently, they never get sick from eating the raw human flesh and blood, the movie never explains exactly what they are, they're very vague about it, are they regular cannibals, or do they have some kind of supernatural like senses and abilities?
I believe the film is a modern take on vampires. They're not vampires per se, but the author ran with some of the themes and applied it within the context of cannibalism.
- It's genetic/born with it. As we see the young girl unable to help herself, her mother before her etc.
- So there is a 'them and us' thing (Eaters or Normals), similar to vampires vs humans (monsters preying/feeding because they have to/feel compelled).
- There could be a degree of 'inducing trances'/hypnosis/putting people under the spell (such as easily persuading the fairground guy), but this is speculation on my part, its just the way it was filmed/close up of eyes etc which leads to to thinking this.
- Heightened senses, smell. A little like vampires having heightened or enhanced abilities.
So yeh, its a folklore thing made modern fable but with grit and realism rather than giving too much special attention to (the folklore). Really it is a romance film, love vs monsters etc. I quite enjoyed it.
Vampire lore and especially its modern interpretation is an allegory to sexual desires. Theres a reason its popularity came about in an era of sexual repression. Its why you see vampires seduce people. The blood drinking is an allegory to defloration.
They didn't show much supernatural ability other than smell.
There would have to be something going on or they would not be able to repeatedly subdue people without getting seriously hurt occasionally.
Chalamet didn't seem to have any trouble taking down that dude in the market who was bigger than him. Yeah, I suppose it's possible Chalamet could get lucky and win that fight, but a normal guy Chalamet's size ain't winning fights like that on the reg