TV age ratings

[Estherpologist]

I'm happy to let our 14yr old DD watch a 15 cert TV show or movie. She's mentioned a couple of 18s she'd like to watch on Amazon. I think they're mainly 18 because of violence. Im uneasy about it though I'm not sure they're much worse than a lot of 12A films.
Where do most people stand on age ratings?

at 14 i'd stick to the 15 age rating after 16 we didn't see how we could stop them but obviously i'd look up what the show actually was first because honestly it's flexible some age ratings are only so high so the movie/tv company doesn't get complaints