@TrainFan2020 Most passenger rail in the UK these days is multiple units which are basically passenger cars with the traction equipment mounted underneath - here is a video I took of one of the most modern ones if you're not sure what I mean and here is someone else's video of one of my favourites (it sounds lovely!)
We certainly don't have steam locos left in mainline service anymore though they occasionally run special railtours with them. There are also preserved railways that run them regularly.
America has a much wider range of rail freight, you're right.
As for the horns, I know there are some points where they have to be sounded such as on the approach to some level crossings but I don't know in much more detail than that!