More than the specific problems with collections that he talks about, I think the problem of allowing clearly broken methods into the standard collections is the real issue.  Why would they accept an implementation f map where map isn&#x27;t safely composable?  Why would they use incorrect type signatures?  Why would they allow so many casts?  I haven&#x27;t finished the video yet but every issue he brings up seems to be about more than a mistake in a library.<p>It looks to me like you can&#x27;t trust Scala because the people behind it are ok with accepting clearly broken or poor quality implementations.