Sentient chickens make no sense

I know it's a cartoon/movie trope, that antropomorphized animals, as the audience sees them, look to the people in the movie's universe like regular animals look to us, but..

..how exactly don't people of this movie's world realize chickens are SENTIENT?

Isn't that one of the big animal flesh-eaters' argument, that because animals are dumb and have no soul/sentience, it's perfectly ethical to brutally and bloodily slaughter them (it's worse than shown in the movie 'Apocalypse Now!') and cause them immense pain and misery just so people can have 'product' that isn't even necessary since there are ethical alternatives?

So how do people in this movie's universe justify eating chickens, that are CLEARLY sentient and can think, organize, form plans, draw blueprings, build planes (!) and on and on..?

I mean, surely there must be SOME 'conspiracy theorist' in 'Chicken Run' universe that tries to tell people that chickens are actually sentient. Surely some 'scientists' would've tested that theory and found it to be true, right?

Surely people wouldn't even have STARTED to treat chickens the way this world treats chickens to begin with, since they're obviously sentient from the get-go!

So why does the female villain of this story think chickens are just as stupid and non-sentient as the chickens of 'our world' are generally thought to be? Why does she tell him it's all in his head, if it's THIS CLEAR that they're sentient?

ALSO!

What the heck do the chickens GAIN by pretending to be dumb animals, when they're really capable of humanlike thinking? If they can whistle, wear glasses and create escape plans, why are they treated like they're just dumb animals?

It makes no sense from any perspective - if chickens really are this sentient, SURELY it would be widely known in this movie's world - people would definitely have found out, at least rumors of it should be already widely circulated, so people might not WANT to buy 'chicken pies', regardless of the 'woman's touch'!

When a movie makes animals sentient and antropomorphic, it's always supposed to be like a nod to the viewer, that we can laugh how animals are not supposed to be like that (but we all supposedly want them to be, so we negotiate with our dogs instead of applying actual dog psychology and then wonder why the dog still gnaws on our petunias and barks at the mailman - yes, I said mailman!)..

..but then we are not supposed to think the _M_A_S_S_I_V_E_ implications of sentient, english-speaking animals. The world would be vastly different, and people absolutely couldn't treat the animals the way people generally treat animals in our world, if they REALLY were that sentient. People would notice.

It kinda works in '101 Dalmatians', because the reason the animals can talk and such, is shown to be from the animals' perspective, so it's partially symbolic, and partially people 'humanizing' the animals, so we hear them bark, but they hear themselves speak english (except with Twilight Bark, which just breaks every rule like this - why can they both bark AND speak english, if all we hear is barking?).

In reality, of course, animals don't communicate 'linquistically', with verbal noises that form words that then form sentences, the way people do, but they communicate with energy and body language, and barking is basically just designed to convey a tone, energy, alert, warning, etc., but not actual DATA as information.

(The same thing applies to 'smoke signals', which are NOT some morse code crap, but just alert that communication is wished, so both sides meditate and communicate more or less telepathically, but this wooshes over nihilistic 'scientists' heads, so pyramids HAVE to be explained as tombs and smoke signals HAVE to be explained as morse code, even though pyramids are really initiation chambers that utilize the pyramid shape's ability to keep things fresh due to the Earth energies and Cosmic energies meeting at the two thirds-point from the ground up - this is why razors stay sharp and food doesn't spoil in a correctly built pyramid)

In any case, almost nothing makes sense in movies, but what else is new, nothing seems to make sense outside movies, either.