Roaming isn't something that those of us who live in more populated areas encounter often, but it can be a common occurrence for people in more rural or less-developed places (or Europe, as many of you have pointed out). Android has always been pretty terrible at showing what kind of data connection you're roaming on in the status bar; thankfully, the latest 7.1.2 Nougat beta has brought this much-needed, yet simple update to this indicator.
Previously, it was impossible to see what type of data connection (LTE, H, 3G, E, etc.) you were on if you were roaming, as the 'R' indicator would take those indicators' place above the signal bars. Now, though, that 'R' has been relocated to the right of those bars, allowing you to see what kind of data speeds you should expect. There was an Xposed module called Roaming Control that allowed tinkerers to replicate this, but Xposed still doesn't work on Nougat.
As you can see from the screenshots above, this behavior is present on both Nexus and Pixel devices. Frankly, I'm not sure why Google took this long to make this easy of a change, but I'm glad it's here now.