ODY757 ... in your first post you have summed up the content of about 382,635 posts in 732 different Threads!! I doubt there will be many who would disagree with your views!
In the final analysis, T5 is just a better building manned by the same sort of staff in the other Terminals. As you note, it is
service levels that remain a constant source of annoyance to the paying pax, especially those in the premium cabins.
A well-run restaurant has a maitre d' who is constantly checking, and kicking, and nudging, and encouraging. That level of hands-on supervision/management seem to be one big factor that is missing, either in the terminal or in the aircraft.