or they just get guidlines beforehand, while signing and producing and stuff, that they have to use Apple products whenever possible...
All in all, there's probably a team in marketing that handles stuff like this, definitely not teams of people in super secret Apple mind control labs.
Guidelines. That is exactly it. When I am working on a show with product placement we will get guidelines on how the product must be placed in frame. Sometimes a product placement will be scripted but, again, it is based on guidelines. In most cases product placement is dealt with through a third party company whose job is to tie productions with products. I doubt, however, that Apple marketing is that far removed from tv+. I also doubt that anyone from Apple is on-set to co-ordinate product placement. This is not a new concept to anyone working on-set, they know how it is done.
For those who are noticing more product placement on all platforms, well, you are right. With the ability to skip commercials on broadcast television and the growing dominance of streaming platforms marketing departments are trying to find ways to get products in front of eyeballs. And whether it works for you as an individual it has been found that product placement is more effective, especially with younger generations, than ads. It is done because it works. Go figure.
I am a huge fan of Terry O'Reilly's CBC podcast
Under the Influence. Check it out, he covers marketing in film and television in a couple episodes at least.