Then how has this happened so many times in the recent past? Its easy to say "a captain wouldn't do X", but I'm having a hard time understanding how this happen

Then how has this happened so many times in the recent past? Its easy to say "a captain wouldn't do X", but I'm having a hard time understanding how this happened without such a level of complacence. Obviously there should be multiple mechanisms, but none of them worked. Why? Also I said GPS or similar. Obviously they shouldn't be relying on AIS data from other ships alone, why did radar not pick it up? Why did the bridge not see it with flir/nv? Something really isn't making sense here.