That wall is to keep people out from another state, not in.

After all, they kept Paul Robeson in by simply pulling his passport, no wall needed.

https://en.wikipedia.org/wiki/Paul_Robeson#:~:text=A%20month...

I don't need to go to Wikipedia to read about Robeson. Guy became a Stalin fan and crumbled mentally when he realised the USSR was not what it claimed. Great singer though.

I think part of what they didn't like was that in Old Man River, instead of singing:

  Git a little drunk
  An' you lands in jail

for Moscow audiences he sang:

  Show a little grit
  And you land in jail

That's how east berlin marketed it too, it still features bi-directional blocking abilities, like all walls.