It probably depends on where you live, then. Where I'm from and from what my brothers told me when they worked at the theater, movie theaters were pretty much policing/shaming parents who were bringing their young kids to Sausage Party ("Because all animated films are for kids!") and Deadpool ("It's a Marvel superhero film!"). One theater even put up a notice on the doors about it. Was pretty nuts.As someone who has worked in movie theaters, we didn't give a solitary iota of a fuck what you saw or how old you were as long as you paid and/or weren't sneaking in. Out of all the times that I've been carded at a theater, only one was for actually seeing a movie, and the rest was when I wanted a beer or something.
The "check the box" adverts I'm sure are by parent groups, but I noticed a few years ago the rating boxes got bigger in trailers, so unless it's just a local thing, I'm assuming it's nationwide.
Rocketman being distributed by Paramount may have something to do with it, unless they left some scenes on the cutting room floor just to get that R-rating (aren't they slightly harsher on gay males than lesbians or am I misremembering things?). 50 Shades apparently had a rule or something to not show (as much) penis to be able to squeak by with an R-rating--but also, Universal may have pulled strings. I only saw This Film is Not Yet Rated once and that was years ago, but one thing that still sticks out to me about it was that although they're not as strict on hetero sex like they are on homo sex (and that they rate sex scenes based on thrust count), if there's so much as a shot of pubic hair in a sex scene, they slap it with an NC-17 rating. Can't remember the movie they talked about in it where they mentioned it (I believe it had Alec Baldwin in it), but I think the producers fought the MPAA over that. That rule might've been lifted in recent years as a result or something.The MPAA also has it out for indie movies, considering that Orgazmo got an NC-17 with no notes, while South Park and Team America, which were released by Paramount, had very detailed notes. There's also the fact that they're still autistic when it comes to stuff like nudity or same sex content in movies, considering that Rocketman is one of the tamest R-rated movies that I've ever seen, and Midsommar came close to an NC-17 just for hanging dong.