It should be a no-brainer as to why being grammatically correct is important. Not just in everyday life, but in film industry as well.
Ever since I l moved to US I have been seeing and witnessing real Americans make simple mistakes in their spelling and grammar. While American-English is my third language, and I always make sure I spell it correctly. And yes, I am the one who WILL correct people who say "there" instead of "they're".
I see it all the time on Facebook in film groups, and very rarely on Actor's Access.
Example: An actor on Facebook posts about himself, marketing his/her new booking or a director who is casting for his/ her film. Or even worse- a starting actor who makes a post like "Yo. I just got into actng. Help.. Wanna be my agent? LOL". And that's not even the worst one!
As for few directors, producers and casting directors... Sometimes they don't know the most basic and fundamental communication skills. There is a lack in details in posts that are polluted with incorrect spelling and grammatical errors. Most often those people don't know how to properly talk with others without looking like a village idiot (a Russian proverb) or a complete fool. I see a lot of times posts like "Casting for my new film. Text me." THAT'S IT. Those are the details. Like, hold on... What type of film is it? Is it PAID? Is it non-union or SAG-AFTRA? Are you looking for males or females? What age? Do you have a link to this casting call? Are you booking off of headshots or do you need resume, demo reel? What's the location? Do you have an IMDb? SO MANY THINGS to put into consideration.
I cringe when I see a casting call that doesn't have any details whatsoever, that it was posted by someone across the country and they are using WhatsApp. First of all- why are you posting in a New York, Chicago, Atlanta group that's based in United States? Second of all- sometimes those "castings" are looking for 18-25 year old females. Do I smell human trafficking?
I'm getting slightly off topic here, but do understand that writing a rough draft in Google Docs or taking an English class is important if you want to be taken seriously in the world. You want to look professional, don't you?