There’s a lot of stuff available in 4K on Blu-ray but not on iTunes yet, it will be to do with licensing issues.

Apple updates movies to 4K all the time, but as I’m sure you can appreciate it’s quite an undertaking to update every movie so it will be 4K eventually.

I’m also building a digital library on the Apple TV app atm, my current method is to look at the 4K page each week and see what 4K movies on offer and buy the ones I like. (4K page isn’t on iTunes, use the Apple TV app).

https://preview.redd.it/ymeiumqyzj2c1.jpeg?width=1284&format=pjpg&auto=webp&s=4bbfc22f943b757a9be3249328ebeb2c060d23aa

Sorry, yes I’m in the UK, should have mentioned that

OP if you can get Time S2 available to stream in the U.S. I’ll see what I can do about Casino in 4K for the UK.