The first quote is simply a statement that central locking is safer. I don't think that's really disputed, but it's not the same as saying that it was the defining motivation, especially in the 1920s.
The second quote relates to the greater adoption in the 1990s. But this is far after the initial adoption by the London Underground in the 1920s, and presumably these safety issues during the period 1920-1990 weren't so great as to be a showstopper, even if a safer design is preferable. This suggests to me that there was some other, much stronger motivating factor behind the development of the technology in the 1920s on the London Underground, with safety being a trailing motivator.
The third relates to a design issue entirely orthogonal to the design of the doors.
The second quote relates to the greater adoption in the 1990s. But this is far after the initial adoption by the London Underground in the 1920s, and presumably these safety issues during the period 1920-1990 weren't so great as to be a showstopper, even if a safer design is preferable. This suggests to me that there was some other, much stronger motivating factor behind the development of the technology in the 1920s on the London Underground, with safety being a trailing motivator.
The third relates to a design issue entirely orthogonal to the design of the doors.