While I agree that rail infrastructure should be improved significantly in Eastern Europe, if you look a bit closer you'll see that there are many other countries where the 5 hrs don't take you much outside of national borders, e.g. Spain, Portugal, Italy, the UK, most of Scandinavia etc.
It's also important to note that Ukraine and Moldova run on a different gauge, so the border crossing takes some time.
The U.K. has nonsense passport and security checks which mean trains only go from london and adds a 60-90 minute connection. Without those you could easily route Manchester, Bristol, Leeds, Birmingham etc via Stratford and the tunnel and into much of north west europe in 5 hours.
It's also important to note that Ukraine and Moldova run on a different gauge, so the border crossing takes some time.