They already do this, listen to the radio at off hours and there will be many job ads with instructions to apply via postal mail. Of course the reason isn't to deter LLMs it's to deter Americans so the employer can claim no Americans applied in their visa and green card filings.
> maybe it’s about control, maybe is someone trying to get a friend hired
Control of the employee is a huge one.
When telling a US citizen they have to work 80s, the citizen can tell you to fuck off and leave for the weekend. The H1B debates the risk of their visa not getting renewed/revoked.
The second issue is a huge problem in some large companies. Instead of a branch being a random assortment of people based on merit it becomes a tight knit group based on loyalty to the person that got them hired with few actual interests in the company itself. These can become serious risks for companies as classism and racism very commonly occur. Also with everyone covering for everyone else fraud and other means of overcoming accounting controls is at higher risk of occurring.
Take a look at the job ads in your local paper's classified section. You'll have to search as classifieds don't have their own section anymore, but it'll be in somewhere.
You'll likely see some listings with very specific and odd instructions to apply. I seem to recall there was a ruling/advisory that requiring application on paper doesn't actually meet the requirements for immigration, but it used to. You would see very detailed and specific requirements, and it would be cumbersome to apply, and the hiring company would be hoping that only the candidate they already knew would apply.
As much hate as H1Bs get, I’ve worked at two large companies where the publicly posted salary range for H1B applications were consistently higher than my own. In all humility, I was more qualified and more experienced than required by the position.
Maybe there is a dearth of talent, maybe it’s about control, maybe is someone trying to get a friend hired. I don’t think it’s about the money.