Some 3d movies add the depth in post, those look like cardboard cutouts, more expensive films use the full 3d camera to record the film, those look much better but are quite rare, especially now the fad is mostly played out (and some movies, like most marvel films, use a mix of the two techniques). I agree the focus thing is an annoying problem and that even with the better version it doesn’t add much.
Some 3d movies add the depth in post, those look like cardboard cutouts, more expensive films use the full 3d camera to record the film, those look much better but are quite rare, especially now the fad is mostly played out (and some movies, like most marvel films, use a mix of the two techniques). I agree the focus thing is an annoying problem and that even with the better version it doesn’t add much.