"strengthen our safety nets, because this era will leave more people behind" -  This isn't just about technological advances eliminating the need for as many workers as before.  It's also about the disadvantage of all advances in technology, the inability of some to adjust.  Invent the spear and maybe all the rock throwers in the tribe can learn this new weapon. Maybe not but then what does the hunter who never masters the spear do, starve?
The question isn't about leaving more people behind, that's inevitable. And the problem isn't just safety nets and, more importantly, who pays for them and how much.  The problem, as many retirees can tell you, is how to fight boredom and uselessness.  Do we care about that?
Even if we needed every available body to fill jobs required by the newest technologies would everyone be able to actually learn and do them?
Neither Trump nor Friedman have answers (Friedman at least admits it).  Trump doesn't even understand the problems.