This is a terrific question, and could be stated more broadly: Does a bridge always have to end on the dominant function? If not, and it ends on its tonic, what makes it "work" since it's going against the tried and true formula? And those examples: Something, Help, Hey Jude, Back in the USSR, Love Me Do... let's think about how the "bridge&...
I would say this song doesn't have a middle eight, but that isn't really important, because you really just need a way to look at form.
The important thing to look for regarding traditional form is tonal center and phrase endings.
Let's look at a basic 32 bar song form...
32 Bar Form
A : I ... V, 8 bars
A' : I ... I, 8 bars
B : ? ... V, 8 bars (the ...
It obviously does work! What reason could there be that it doesn't? There is nothing in the 'rules' that says there must be a dominant before starting the next verse. True, there often is, but that's no criterion.
In fact, there are several songs where the middle eight/bridge ends on tonic, but the next verse starts somewhere different!
The reason so many ...
The middle 8 or bridge of a song is there to provide some contrast to the song but it doesn’t have to end on a dominant even though it often does. In fact there are no rules governing how a bridge should end, it is up to the composer. In the case of the Beatles bridges end on the tonic fairly regularly:
Back in the USSR
Love Me Do